Time Calculator: Add, Subtract, and Compute Time Differences Instantly

A time calculator sits at the intersection of practicality and precision — whether you need to add time, subtract time, find time difference, or simply calculate time between dates, having the right tool makes the entire process seamless. In professional settings, individuals and organisations alike rely on these calculators to manage schedules efficiently, plan activities across multiple time zones, and measure durations with accuracy. The input fields, when left blank, default to 0, so you can begin calculations immediately without setup friction. What makes a good time-to-time calculator genuinely useful is how it handles basic operations on time — letting you add, subtract, and surface the differences between two time values without manual conversion errors. From tracking time duration in days, hours that have passed, to working out the gap between something like March 2 2010, 11:00 am and April 3 2010, 6:30 pm, these tools serve a pivotal role in how we interact with time daily. Beyond the time and date calculator itself, related tools such as the Date Calculator, Countdown Calculator, Speed Distance Time Calculator, Average Calculator, and broader Utility Calculator Category extend this ecosystem, covering virtually every time-related computation you’d encounter.

The numbers produced — including decimal numbers — are organized clearly, often presented in a table of common units so you always understand what the calculations represent. That table typically maps every major time unit from largest to smallest: a millennium spans 1000 years; a century, 100 years; a decade, 10 years. A year on average runs 365.242 days with 12 months — the common year holding 365 days and the leap year stretching to 366 days. A quarter covers 3 months; each month runs 28-31 days depending on the calendar: Jan, Mar, May, Jul, Aug, Oct, Dec each carry 31 days; Apr, Jun, Sep, Nov hold 30 days; and Feb gives either 28 days or 29 days in a leap year. A week is 7 days; a day, 24 hours, 1440 minutes, and 86400 seconds. An hour equals 60 minutes or 3600 seconds; a minute, 60 seconds. The second is the base unit, beneath which sit the millisecond (10⁻³ second), microsecond (10⁻⁶ second), nanosecond (10⁻⁹ second), and picosecond (10⁻¹² second). Understanding this hierarchy is the foundation for using any time tool with real confidence — something you appreciate more once you’ve caught a costly scheduling error that a manual calculation quietly introduced.

The world runs on the understanding that every second counts — whether you race against time on a project deadline, feel like you live on borrowed time between commitments, work overtime to close a gap, go through a rough time juggling competing priorities, or simply hardly have time to breathe during a demanding quarter. Even the lighter moments — when you dance out of time during a presentation or kill time before a meeting — underscore just how universal time problems are. A reliable time calculator helps you stop trying to waste the hours in an offhand way and instead manage every time constraint deliberately. The instructions to use and calculate time manually have their place in learning, but for recurring operational needs, this article makes the case that the right tools — and knowing how to leverage them effectively — genuinely save you both headaches and hours. Whether your needs are personal or enterprise-level, these calculators turn what was once a time race into a controlled, informed process.

◊ Time Unit	◊ Definition	◊ Equivalent Values
Millennium	1,000 years	—
Century	100 years	—
Decade	10 years	—
Year (Average)	365.242 days	12 months
Common Year	365 days	12 months
Leap Year	366 days	12 months
Quarter	3 months	—
Month (Long)	31 days	Jan, Mar, May, Jul, Aug, Oct, Dec
Month (Standard)	30 days	Apr, Jun, Sep, Nov
February (Common)	28 days	Non-leap year
February (Leap)	29 days	Leap year only
Week	7 days	—
Day	24 hours	1,440 minutes / 86,400 seconds
Hour	60 minutes	3,600 seconds
Minute	60 seconds	—
Second	Base unit	—
Millisecond	10⁻³ second	0.001 second
Microsecond	10⁻⁶ second	0.000001 second
Nanosecond	10⁻⁹ second	0.000000001 second
Picosecond	10⁻¹² second	0.000000000001 second

 

How Philosophers and Scientists Have Understood the Concept of Time

Ancient Greece

Aristotle, 384-322 BC, stands as one of the most consequential ancient Greek philosophers to have engaged seriously with the question of what time actually is. Where earlier thinkers had touched on it loosely, Aristotle was among the first to attempt a rigorous definition — he defined time as the number of movements with respect to before and after, tying its existence entirely to motion. In his framework, time could not exist without change — a view that set the terms of debate for an extensive period of human history. His concepts were not merely academic; they shaped how philosophers and scientists after him framed every subsequent inquiry into measurement, motion, and duration.

What made Aristotle’s position genuinely provocative was his stance on whether time is infinite and continuous — and whether the universe would always exist. He leaned toward time having no beginning or end, which made the notion of non-existence of time both questionable and controversial to later thinkers shaped by different traditions. These earlier views laid the intellectual groundwork that Sir Isaac Newton and Gottfried Leibniz would each build upon — and sharply disagree over — centuries later.

Newton & Leibniz

Newton’s treatment of time in Philosophiæ Naturalis Principia Mathematica remains one of the boldest claims in the history of science: that space and time are absolutes. Absolute time, in his view, flows independently of external factors — it moves uniformly whether or not any objects, humans, or celestial bodies like the sun and moon are there to perceive it. This duration exists mathematically even when it is imperceptible. Relative time, by contrast, is what humans experience — the measurement of motion against observable reference points. This Newtonian time represented a firmly realist view of the universe, and it remained prevalent for over two centuries.

Leibniz rejected this entirely. His relational time argued that time and space are not containers that exist independently but are simply numbers we use to compare and sequence events — defined only through their relationships. Time, in his view, is subjectively constructed from experiences accumulated across lifetimes. This debate played out formally in their correspondence through Samuel Clarke, Newton’s proxy. The famous bucket argument — Newton’s bucket — describes a water-filled bucket hanging from a rope: when stationary, the water has a flat surface; as it begins to spin, rotation causes the surface to become concave; even when the rope is stopped, concavity persists. Newton used this to argue that rotating motion is measured against absolute space, not relative objects — a direct challenge to the relationalist perspective. Leibniz countered through the lens of acceleration and relational interaction, but Newton’s framework dominated until a far more radical rethinking arrived.

Einstein

Albert Einstein didn’t merely refine Newton — he structurally overturned one of the most well-conceived theories in scientific history. Drawing on the work of Ernst Mach, Albert A. Michelson, Hendrik Lorentz, and Henri Poincaré, and formalising the mathematics through the Lorenz Transformation, Einstein’s theory of relativity dissolved the boundary between space and time, recasting them as spacetime — connected, not separate. The core claim was that time is relative to the speed of light, denoted c, measured in a vacuum, and that observers in different inertial frames of reference with different relative velocities will experience different shape and measurement of time. A spaceship moving fast enough will register slower time relative to a stationary observer — not as an illusion, but as physical reality — while c itself remains constant for all observers, an absolute constant that neither faster nor slower motion can alter.

His general relativity extended this further into astronomy and theoretical physics: curved spacetime replaces the flat geometry Newton assumed, and what we experience as gravitational force on the surface of a planet is reinterpreted as movement along a geodesic — the natural path through curved space. The rotating bucket and concave water surface that Newton used to defend absolute space finds a new reading here, as does the concept of an inertial frame in free fall. In the centuries since, advances in quantum physics have further complicated the picture — how time behaves at the quantum scale remains one of the deepest open questions in science. What Einstein demonstrated, and what studying these past frameworks confirms, is that even the most durable ideas humanity builds around time are open to revision when the evidence demands it.

How We Measure Time

The calendar and the clock represent two distinct forms of measurement that together define how civilisations have structured existence around time. What most people never think about is the numerical system quietly underpinning the clock face they glance at daily — the sexagesimal numeral system, or base 60, which traces back to ancient Sumer in the 3rd millennium BC and was carried forward by the Babylonians for calculating angles and geographic coordinates. The reason this system endured is mathematical, not arbitrary: 60 is a superior highly composite number with 12 factors, making it more versatile than any comparable natural number when working with divisors and fractions — a genuine mathematical advantage that still holds.

That advantage becomes immediately visible when you consider how cleanly 1 hour of 60 minutes can be evenly divided: into 30, 20, 15, 12, 10, 6, 5, 4, 3, 2, and 1 minute — no remainders, no awkward conversions. No base-10 equivalent offers that kind of flexibility. The Babylonians applied this to the heavens; we inherited it for the clock. A modified form of this system has remained in continued use today, which is why any serious exploration of how we measure time has to start here — before the devices, before the calendars, with the numerical logic that made precision possible in the first place.

Development of the Second, Minute, and Concept of a 24-Hour Day

Egyptian civilization holds the distinction of being the first civilization to divide the day into smaller parts, using sundials as the earliest documented evidence of structured timekeeping. They split the period between sunrise and sunset into 12 parts, then applied a parallel logic to the passage of night — with Egyptian astronomers tracking stars across 12 divisions — arriving at the 24-hour day we still use. Early hours were not equal; summer hours were longer than those in winter, since the divisions tracked daylight rather than fixed duration. It was Hipparchus, a Greek astronomer working from approximately 147 to 127 BC, who proposed the reform: 12 hours daylight and 12 hours darkness anchored to the equinox, producing equinoctial hours of equal length. These fixed-length hours only became practically enforceable with the arrival of mechanical clocks in the 14th century.

The finer divisions — the minute and the second — owe their existence to Claudius Ptolemy, who applied the Babylonian system of 60 parts to the 360 degrees of longitude lines and latitude, giving us the layered subdivision that flows from degree to minute to second. That same logic translated directly into time. The Gregorian calendar, introduced by Pope Gregory XIII in 1582, corrected the drift built into the Julian calendar established by Julius Caesar in 45 BC as a Roman solar calendar — a system that misaligned with astronomical equinoxes and solstices by roughly 11 minutes per year, a discrepancy that accumulated into a visible calendar shift across civilizations over centuries. Understanding these layered calendar systems also explains why a modern date calculator must account for historical calendar reforms when computing spans that cross the 1582 boundary.

Early Timekeeping Devices

The history of early devices for measuring time reflects the ingenuity of every culture and location that needed to divide day and night into usable periods — for work, for religious practices, and for coordination. Before precision was achievable, oil lamps and candle clocks tracked the passage of time through predictable rates of consumption. The water clock, known as the clepsydra, became the dominant instrument across the ancient world because it offered something genuinely accurate for its era: a regulated flow of water from one container into another that could be measured against marked intervals. Hourglasses and sandglasses followed a similar principle and remained in practical use well into the 14th century, valued for their portability and ability to calibrate specific periods without reference to the sun.

The step-change came with the pendulum mechanical clock, invented by Christiaan Huygens in 1656. By harnessing the natural period of oscillation of a swinging pendulum, Huygens produced a mechanism with errors of fewer than 10 seconds a day — an extraordinary leap from anything that came before. From there, the trajectory ran toward atomic clocks, which regulate time using an electronic oscillator locked to cesium atomic resonance. The cesium atom’s response to radiation defines the SI unit of the second at a level of precision no mechanical system can approach, making atomic clocks the most accurate instruments for time measurement ever refined by science — and the invisible backbone of GPS, global finance, and internet infrastructure today.

Formula Used

• Hours = End Hour − Start Hour
• Minutes = End Minutes − Start Minutes
• Seconds = End Seconds − Start Seconds
• If Seconds < 0 — subtract one minute from Minutes, add 60 to seconds
• If Minutes < 0 — subtract one hour from Hours, add 60 to minutes
  

How to Use a Time Calculator

An online time calculator is easy to use across both web apps and mobile platforms, thanks to an interactive interface designed to deliver results with minimal friction. You simply input specific times and dates, select the type of calculation you need, and configure any additional settings such as time zones or date adjustments — making it equally practical for people coordinating international meetings or tracking long-running projects.

• Choose the type of calculation you want to do
• Input your start and end times
• Apply other settings like time zones or date adjustments for whatever is necessary
• Verify the result calculated for accuracy
• Accuracy: Calculate time intervals using a calculator to avoid human mistakes
• Ease of use: The time duration calculator can help measure hours and minutes easily
• Universal applicability: Whether you are looking for an hour calculator or a time difference calculator for a global event, these calculators can serve many purposes

Types of Time Calculators

Time Duration Calculator

A time duration calculator calculates the total time elapsed between two events — whether you need to track the duration of a meeting, a project, or any scheduled activity — by simply inputting the start and end times and letting the calculator type handle the rest.

Time Difference Calculator

A clock time difference calculator takes the complexity out of calculating the time difference between two geographical locations across varying time zones, making it perfect for anyone coordinating across borders without the guesswork.

Time Calculator Online

Digital calculators have made time-related tools far more convenient — accessible from any electronic device, they reduce workload for students, businesspeople, and travellers alike, giving every type of user a clear advantage over manual computation.

Calculating Time Difference

Understanding time differences requires good planning and a proper understanding of how to calculate between start and end times or time zones being compared. The most reliable approach is using an online time calculator or a spreadsheet programme like Excel, where built-in functions such as =TEXT(end_time-start_time, “hh: mm”) handle the difference between two times and return a clean result — eliminating the manual effort entirely and reducing the risk of error across the steps involved.

• Write down the start and end times or the time zones to be compared
• Use an online time calculator or a spreadsheet programme like Excel to make it easier
• The difference between the two times is the result

Uses of a Time Calculator

From coordinating international conferences to managing personal schedules, a time calculator serves people who work across contexts where precision matters — whether that’s a time difference calculator used to set up conferences across time zones, a manager relying on duration data to allocate resources during project planning, students who need to calculate time spent studying or in extracurricular activities for academic studies, or travellers navigating time differences between countries to keep their itineraries smooth.

• International Conferences: People who work across time zones rely on a time difference calculator to set up conferences
• Project Planning: Calculating the duration helps the manager allocate resources
• Academic Studies: Students often calculate time spent studying or in extracurricular activities
• Travelling: Understanding time differences between countries makes itineraries smooth

Advanced Features in Time Calculators

Modern advanced calculators go well beyond basic arithmetic, offering features that make complex scheduling genuinely effortless — from automatic time zone detection and integration with calendars for real-time scheduling, to the ability to calculate the difference between two times in complex formats that standard tools simply cannot handle.

• Automatic time zone detection
• Integration with calendars for real-time scheduling
• Options to calculate the difference between two times in complex formats

How to Use the Time Difference Calculator

A time difference calculator takes the guesswork out of comparing start and end times across varying time zones — you simply enter each entry into the respective fields, hit calculate, and receive the exact time difference instantly. Designed to simplify hour-based tasks and time-sensitive tasks alike, it functions as an indispensable tool whether you’re using it as a time calculator hours tracker or a time duration calculator built for precision and efficiency — making it equally reliable for the professional, the student, and the traveller managing time-related tasks through any time calculator online. Used consistently, it has the potential to transform perfect time management from an aspiration into a habit that can significantly improve your life.

• Input the start and end times in the respective fields
• Select the time zones for each entry
• Hit “Calculate” to find the exact time difference

Add Time Calculator

The add time calculator works by letting you select a unit and input a value for each task, accepting numbers across up to 20 rows — with new rows appearing automatically as you fill in the last field — and each entry can carry different units, with the result displayed in whichever format you choose through the time calculator. To put it in practical terms, imagine feeding your rabbit takes 12 min, cooking dinner runs 1h 15 min, and calling Uncle Bob clocks in at 53 min — the calculator adds your total evening tasks across hours, minutes, and seconds, filling any blank place at the bottom with zeros and returning a clean 2 h 20 min.

• Choose the unit of your value and input it
• Proceed with all your numbers — you can enter up to 20; new rows will appear as you fill in the last field, and the values can have different units
• Choose the unit in which you want the result to be displayed — you’ll find it in the last field of the time calculator
• Feeding your rabbit — 12 min
• Cooking dinner — 1h 15 min; and
• Calling Uncle Bob — 53 min (he does like to natter on)

Subtract Time Calculator

The subtract time calculator — which doubles as a time difference calculator — follows a straightforward sequence: set the first field to “subtract time”, choose your unit, enter your values, and let the last field surface the result automatically, making it one of the most intuitive ways to calculate duration between times without manual arithmetic. A practical example: if you want to know how many hours of your day remain after deducting time for sleep, set the unit in the first value field to days, enter 1, then input your sleeping hours — say 7h 23 min — into the second value field of the time duration calculator, and the waking hours returned will be 16 h 37 min. For tracking the duration between two specific times, convert both to 24-hour format, enter the later time in the first field and the earlier time in the second row, and the result appears in the last field of the time calculator.

• Change the value of the first field (“I want”) to “subtract time”
• Let’s say you want to know how many hours of the day you have left after deducting time for sleep — change the unit in the first value field to days and enter 1
• In the second value field of the time calculator, input the number you want to deduct — in this example, your sleeping hours, let’s say 7h 23 min
• The result will appear in the last field of the subtract time calculator — in our example, that would be your waking hours: 16 h 37 min
• Convert both times to 24-hour format
• Enter the later time in the first field
• Enter the earlier time in the second row
• The result will appear in the last field of the time calculator

Multiply Time Calculator

The multiply time calculator is built for situations where you know a partial duration and need to scale it up — you set the first field to “multiply time”, enter the time value you want to multiply as the multiplicand in the second field, then drop the multiplier into the third row, and the result surfaces automatically in the last field with full flexibility to switch units at any point. A practical illustration: imagine you’re painting a fence and completing 1/5 of the work takes 23 minutes — to estimate the time for the whole fence (5/5), which will take five times longer, you simply enter those values and the calculator returns 1 h 55 min without a single manual conversion.

• In the first field, choose the “multiply time” option
• In the second field, enter the multiplicand — the time value you want to multiply
• Enter the multiplier into the third row of the multiply time calculator
• The result will appear in the last field — you can freely change the units anytime
• In the second field of the multiply time calculator, enter “23 minutes”
• In the next field, enter “5” (1/5 took 23 min, so the whole fence (5/5) will take five times longer)
• You’ll see the result is 1 h 55 min

Time Calculator — Division

The divide time calculator — also referred to as a time division calculator — reverses the scaling logic: set the first field to “divide time”, enter the numerator (the time value you want to divide) in the second field, place the denominator into the third row, and the result appears in the last field with the option to toggle units freely throughout. Consider a two-week holiday where 1/3 of your sleeping hours are traded for beach time — change the unit in the second field to weeks, enter 2, then divide by 3 in the third field of the time division calculator, and the result tells you you’ll spend 112 h by the sea — or 4 days and 16 hours of pure tan-building time with your beloved.

• In the first field, choose the “divide time” option
• In the second field, enter the numerator — the time value you want to divide
• Enter the denominator (the number by which you divide) into the third row of the time division calculator
• The result will appear in the last field — you can change the units in the time division calculator
• Change the unit in the second field to “weeks” — enter “2”
• To find how much is 1/3 of the time, you need to divide by 3 — enter this number into the third field of the divide time calculator
• The result at the bottom says you’ll spend 112 h by the sea with your beloved — change the unit to see if this equals 4 days and 16 hours — enough to top up that tan!

How to Add Time Manually

Adding time manually demands a shift in thinking — unlike the decimal system where 10, 100, or 1000 smaller units make one larger (as in 10 grams equalling 1 dekagram), the hexadecimal system governing time runs on 60 smaller units to 1 bigger unit: 60 seconds to 1 minute, 60 minutes to 1 hour — a distinction that shapes every step of time addition. Working through an example clarifies the procedure: adding 1 h 53 min and 2 h 8 min 22 s with 46 s produces raw totals of 3 h, 61 min, and 68 s, which then need to convert — 68 s becomes 1 min 8 s, and 61 min becomes 1 h 1 min — before you substitute these back into the formula to arrive at the clean result: 4 h 2 min 8 s.

• Add minutes to minutes, hours to hours, and seconds to seconds
• Convert where possible
• Substitute the converted values from step 2 into the formula
• Add hours, minutes, and seconds separately
• When there’s nothing left to add, write down the result
• If there is a need to convert values, repeat the procedure from step 2

How to Subtract Time Without the Time Calculator

Rather than relying on a time calculator, subtract time manually using one of two clean approaches — the first method is to convert everything to the smallest unit occurring in the values, so subtracting 11 min 55 s from 1 day means converting to 86400 s and 715 s respectively, subtracting to get 85685 s, then converting back to 23 h 48 min 5 s; the second method uses long division logic, breaking the bigger number into a sum of parts — splitting 24 h into 23 h and 1 h, 60 min into 59 min and 1 min, 60 s into the remaining seconds — subtracting minutes from minutes and seconds from seconds until you reach the desired unit and arrive at your final result through a clean expression.

• Convert time values to the smallest unit occurring in them
• Subtract the converted values
• Convert the result to the desired unit
• Break the bigger number into a sum of parts from which you can easily subtract
• Subtract from the expression you got in the first step (minutes from minutes, seconds from seconds, etc.)

How to Calculate Time — Multiplication

Multiply each unit of time through multiplication separately — working through 3 h 43 min 11 s multiplied by 6 gives raw figures of 18 h, 258 min, and 66 s, each of which then needs to convert: 66 s becomes 1 min 6 s and 258 min becomes 4 h 18 min — then you add all converted units together following the same procedure to arrive at the clean final answer of 22 h 19 min 6 s.

• Multiply each unit separately
• Convert each unit if possible
• Add the converted units
• Convert your time again if there is a need (step 2)

How to Calculate Time — Division

Division across time units follows a layered conversion procedure — to divide 3 weeks by 5, start with the numerator and break it into a smaller unit: 3 weeks becomes 21 days via 7 days, then 504 h via 24 h, then 30240 min via 60 min, at which point you can cleanly divide by 5 to get 6048 min, which converts back through 100 h 48 min to the desired unit of 4 days 4 h 48 min. For date-based calculations, a date calculator handles time between dates with the same step-by-step logic — follow the instructions provided within the tool to convert at each stage without losing precision.

• Convert the numerator to a smaller unit until you get a number that can be divided by 5
• Do the division
• Convert to the desired unit

FAQ’s:

What Is the Time Difference?

A time difference is the gap between two clock times — most commonly used in the context of geographical time zones to establish how far apart two locations sit on the global clock.

How Do I Calculate the Time Difference?

A clock time difference calculator is the fastest route, but you can also do it manually — simply subtract one time from another to find the gap between them.

How to Calculate Time?

To calculate time, identify your starting and ending points, then subtract the smaller value from the larger to determine the duration between them.

How to Calculate Time Difference in Excel?

Excel handles time differences cleanly through built-in formulas — the most commonly used is =TEXT(end_time-start_time,”hh:mm”), which returns the gap in hours and minutes instantly.

How to Calculate the Time Difference Between Two Countries?

Use a time difference calculator that takes time zones into account — input the zones for your two countries and the result is returned automatically.

How to Calculate the Time Difference Between Two Longitudes?

Since the Earth is divided into 360 longitude degrees and rotates over 24 hours, every 15° of longitude equals 1 hour of time — to calculate the difference between two longitudes, simply convert the degree gap using that ratio.

How Many Seconds Are in a Day? How Many Seconds Are in a Year?

There are 86400 seconds in a day — derived by working up from the base: a minute equals 1 min = 60 s, an hour equals 1 h = 60 min, and a day runs 24 h, so you multiply them as 1 d = 24 h × 60 min/h × 60 s/min = 86400 s; scaling that across 365 days gives 1 y = 86400 s/d × 365 d = 31536000 s.

• Take the number of seconds in a minute: 1 min = 60 s
• Take the number of minutes in an hour: 1 h = 60 min
• Take the number of hours in a day: 1 d = 24 h
• Multiply these values: 1 d = 24 h × 60 min/h × 60 s/min = 86,400 s

Why Are There 60 Seconds in a Minute and 60 Minutes in an Hour?

The reason humanity still counts time in 60 seconds per minute and 60 minutes per hour is a direct heritage from early civilization — specifically the Mesopotamian cultures of the Sumerians and Babylonians, who favoured base 60 over base 10 because it is far less complex to work with in practical math: it divides evenly across angles, clocks, maps, and numbers in ways that no comparable base manages as cleanly.

How Do I Calculate the Days Passed Between Two Dates?

To calculate time between two dates — expressed as d1-m1-y1 and d2-m2-y2 — you work in three layers: first subtract the years (y2 − y1) to isolate whole years, then apply the formula (12 − m1) + (m2 − 1) to count the months, and finally sum the remaining days as d2 + (Nm1 − d1) where Nm1 is the days in month m1 — multiply the years and months by 365 and 30.5 respectively for an approximated total across all steps.

• Subtract the two years and subtract 1: y2 − y1 − 1 — this is the number of “whole years”
• Sum the number of whole months with the formula (12 − m1) + (m2 − 1)
• Sum the number of remaining days: d2 + (Nm1 − d1), where Nm1 is the number of days in month m1

How Do You Calculate the Number of Hours You Spend Commuting in a Month?

If you commute 20 days a month with each trip taking 35 minutes, calculating your total commuting hours is a straightforward three-step process — count your journeys, multiply by the duration, then divide by 60 to convert minutes into hours, giving you 23.33 hours a month that could otherwise go toward reading, productive activities, or any number of personal benefits once you compute the true duration of your daily travel.

• Count the number of journeys you took: 20 × 2 = 40
• Multiply the number of journeys by the duration of the trip: 40 × 35 min = 1400 min
• Divide the result by 60, the number of minutes in an hour: 1400/60 = 23.33