★ TIME & DATE · DURATIONS · ADD, SUBTRACT & CONVERT
On the defaults — 2 hours 45 minutes + 1 hour 30 minutes — the total is 4 hours 15 minutes, 255 minutes, 4.250000 decimal hours. Put in two durations and the calculator adds or subtracts them, or converts minutes into hours and minutes — 150 minutes is 2 hours 30 minutes. This one adds, subtracts and converts durations in one place: the hours-between-times-calculator page is the TIME BETWEEN — elapsed time between two clock times — not durations added together; the days-between-dates-calculator page is the DAYS — spans between dates — not hours and minutes; the average-time-calculator page is the AVERAGE — the mean of several durations — not one sum; and the decimal-time-conversion page is the DECIMAL — hours and minutes to decimal hours — not a duration added or subtracted. No time calculator exists on this site — this one is the first.
Adding time is adding minutes: 2 hours 45 minutes is 165 minutes, 1 hour 30 minutes is 90 minutes, and 165 plus 90 is 255 minutes — 4 hours 15 minutes, 4.250000 decimal hours, 15,300 seconds. Subtracting works the same way: 5 hours 30 minutes minus 2 hours 15 minutes is 3 hours 15 minutes, 195 minutes. Converting is dividing by 60: 150 minutes is 2 hours 30 minutes, because 150 divided by 60 is 2 with 30 left over. The calculator shows all of it with notes, never hides it.
It means 2 hours 45 minutes plus 1 hour 30 minutes is 4 hours 15 minutes: the first duration is 2 × 60 + 45 = 165 minutes, the second is 1 × 60 + 30 = 90 minutes, and 165 + 90 = 255 minutes, which is 4 hours and 15 minutes left over. The same total is 4.250000 decimal hours — 255 divided by 60 — and 15,300 seconds — 255 times 60 — and in compact form it is 4h 15m. The hours and minutes are just two ways of writing the same 255 minutes: the hours are how many whole 60s fit, the minutes are what is left.
Minutes are 0 to 59, or the sum is wrong. A duration written as 2 hours 75 minutes is really 3 hours 15 minutes — the 75 minutes holds a whole hour — and the calculator refuses minutes of 60 or more instead of adding them as written. If it complains, rewrite the duration properly: carry every 60 minutes into an hour, then add.
Adding and subtracting are different questions. Adding stacks two durations into a longer one; subtracting finds what is left after the second is taken from the first. Subtracting a longer duration from a shorter one has no answer in durations — 2 hours minus 3 hours is not minus 1 hour — so the calculator refuses it and says the second duration is longer than the first. Check which duration is which before you trust a subtraction.
Decimal hours are not hours and minutes. 4.25 hours is 4 hours 15 minutes, not 4 hours 25 minutes: the .25 is a quarter of an hour, and a quarter of 60 minutes is 15. The same trap the other way: 4 hours 25 minutes is 4.416667 decimal hours, not 4.25. If a timesheet wants decimals, use the decimal-hours figure on this page; if it wants hours and minutes, use the words.
On the defaults: add 2 hours 45 minutes and 1 hour 30 minutes.
The defaults are add mode, 2 hours 45 minutes plus 1 hour 30 minutes — two ordinary durations, an afternoon of work and a meeting, say — and the total is 4 hours 15 minutes, 255 minutes, 4.250000 decimal hours. They are a starting point, not a standard: your durations may be minutes only, or a whole day, or a subtraction, and the right answer for you is the one your numbers describe. Change the mode, the hours, the minutes and the convert value to your own and the calculator recomputes instantly. Turn each duration into minutes, add or subtract, and turn the answer back into hours and minutes.
These notes repeat in every explainer section because this page is built to be read start to finish: the defaults are one sum, not a standard; minutes are 0 to 59, or the sum is wrong; adding and subtracting are different questions; and decimal hours are not hours and minutes.
| Output | Formula | What it means |
|---|---|---|
| Mode | input | add. |
| First duration, hours | input | 2. |
| First duration, minutes | input | 45. |
| Second duration, hours | input | 1. |
| Second duration, minutes | input | 30. |
| Minutes to convert | input | 150. |
| Total (minutes) | first + second | 255. |
| Total | hours & minutes | 4 hours 15 minutes. |
| Total (compact) | h & m | 4h 15m. |
| Decimal hours | total ÷ 60 | 4.250000. |
| Seconds | total × 60 | 15,300. |
| Verdict | in words | 2 hours 45 minutes + 1 hour 30 minutes = 4 hours 15 minutes. |
| Reverse: Smallest time to add to 2 hours 45 minutes for a total of at least 5 hours | step | 2 hours 15 minutes: 2 hours 45 minutes + 2 hours 15 minutes = 5 hours (total 300 minutes). |
| Reverse: Largest time to subtract from 5 hours 30 minutes leaving at least 3 hours | step | 2 hours 30 minutes: 5 hours 30 minutes − 2 hours 30 minutes = 3 hours (total 180 minutes). |
| Reverse: Smallest minutes to convert for at least 2 hours 30 minutes | step | 150 min: 150 minutes = 2 hours 30 minutes (150 minutes). |
| Reverse: Smallest second duration for 3 hours 20 minutes to reach at least 8 hours | step | 4 hours 45 minutes: 3 hours 20 minutes + 4 hours 45 minutes = 8 hours 5 minutes (total 485 minutes). |
| Reverse: Largest time to subtract from 8 hours leaving at least 4 hours | step | 4 hours: 8 hours − 4 hours = 4 hours (total 240 minutes). |
| Reverse: Smallest first duration with 1 hour 30 minutes to reach at least 6 hours | step | 4 hours 30 minutes: 4 hours 30 minutes + 1 hour 30 minutes = 6 hours (total 360 minutes). |
| 1 hour + 30 minutes | same model | 1 hour + 30 minutes = 1 hour 30 minutes. |
| 3 hours 20 minutes + 2 hours 40 minutes | same model | 3 hours 20 minutes + 2 hours 40 minutes = 6 hours. |
| 5 hours 30 minutes − 2 hours 15 minutes | same model | 5 hours 30 minutes − 2 hours 15 minutes = 3 hours 15 minutes. |
| 90 minutes to convert | same model | 90 minutes = 1 hour 30 minutes. |
| 45 minutes + 45 minutes | same model | 45 minutes + 45 minutes = 1 hour 30 minutes. |
| 10 hours + 5 hours 59 minutes | same model | 10 hours + 5 hours 59 minutes = 15 hours 59 minutes. |
| 8 hours − 3 hours 30 minutes | same model | 8 hours − 3 hours 30 minutes = 4 hours 30 minutes. |
| 61 minutes to convert | same model | 61 minutes = 1 hour 1 minute. |
| 23 hours 59 minutes + 2 minutes | same model | 23 hours 59 minutes + 2 minutes = 24 hours 1 minute. |
| 1 hour 7 minutes + 2 hours 23 minutes | same model | 1 hour 7 minutes + 2 hours 23 minutes = 3 hours 30 minutes. |
| 0 minutes plus 0 minutes | same model | 0 minutes + 0 minutes = 0 minutes. |
| 1 minute plus 1 minute | same model | 1 minute + 1 minute = 2 minutes. |
| 0 minutes to convert | same model | 0 minutes = 0 minutes. |
| 1440 minutes to convert | same model | 1440 minutes = 24 hours. |
| 3 hours minus 3 hours | same model | 3 hours − 3 hours = 0 minutes. |
| 2 hours minus 3 hours | same model | The second duration is longer than the first.. |
| 59 minutes plus 59 minutes | same model | 59 minutes + 59 minutes = 1 hour 58 minutes. |
| 59 minutes to convert | same model | 59 minutes = 59 minutes. |
| 12 hours 30 minutes plus 12 hours 30 minutes | same model | 12 hours 30 minutes + 12 hours 30 minutes = 25 hours. |
| 45 minutes plus 20 minutes | same model | 45 minutes + 20 minutes = 1 hour 5 minutes. |
| 10080 minutes to convert | same model | 10080 minutes = 168 hours. |
The calculator counts in exact whole minutes — every total on this page is checked against an independent model, and the minutes are integers, so there is no rounding to mislead you except the decimal-hours display, which is printed to 6dp (4.250000 for the headline). What it cannot do is count seconds: the inputs are whole minutes only, and a duration of 2 hours 45 minutes 30 seconds has to be rounded to minutes first, which the calculator will not do for you. It also counts durations, not clock times — 12 hours 30 minutes plus 12 hours 30 minutes is 25 hours, which is correct as a duration and meaningless as a time of day, and it never wraps past midnight. Subtracting a longer duration is refused rather than printed negative, because a negative duration is not a duration. It is not a timesheet: tax, overtime rules and rounding to the nearest quarter hour are your employer’s, not this page’s.
2 hours 45 minutes + 1 hour 30 minutes = 4 hours 15 minutes. Smallest time to add to 2 hours 45 minutes for a total of at least 5 hours: 2 hours 15 minutes. Largest time to subtract from 5 hours 30 minutes leaving at least 3 hours: 2 hours 30 minutes. Smallest minutes to convert for at least 2 hours 30 minutes: 150 min. Smallest second duration for 3 hours 20 minutes to reach at least 8 hours: 4 hours 45 minutes. Largest time to subtract from 8 hours leaving at least 4 hours: 4 hours. Smallest first duration with 1 hour 30 minutes to reach at least 6 hours: 4 hours 30 minutes. Source: Bright Side Kit, brightoolbox.com.
Turn each duration into minutes, add, then turn the answer back into hours and minutes. 2 hours 45 minutes is 165 minutes, 1 hour 30 minutes is 90 minutes, and 165 + 90 = 255 minutes, which is 4 hours 15 minutes. Put your durations into the calculator above and it does the carrying for you.
Turn each duration into minutes and subtract: 5 hours 30 minutes is 330 minutes, 2 hours 15 minutes is 135 minutes, and 330 − 135 = 195 minutes, 3 hours 15 minutes. The calculator refuses the subtraction if the second duration is longer than the first — 2 hours minus 3 hours has no answer in durations.
Divide by 60: the whole part is the hours and the remainder is the minutes. 150 minutes is 2 hours 30 minutes, 61 minutes is 1 hour 1 minute, and 1,440 minutes is 24 hours. Put the minutes into convert mode above and the calculator gives the hours and minutes, the decimal hours and the seconds.
4 hours 15 minutes: the .25 is a quarter of an hour, and a quarter of 60 minutes is 15. The same rule the other way: 4 hours 25 minutes is 4.416667 decimal hours, not 4.25, because 25 minutes is 25 ÷ 60 of an hour.
Add the durations two at a time, carrying the minutes into hours as you go: 23 hours 59 minutes plus 2 minutes is 24 hours 1 minute, and the total can pass 24 hours, because a week of durations is not a clock time. Keep the running total in minutes if you are adding by hand — 1,441 minutes is easier to carry than 24 hours 1 minute.
Because the second duration is longer than the first: 2 hours minus 3 hours would be minus 1 hour, which is not a duration. Swap the two durations if you meant the other way round, or check the inputs — the usual mistake is putting the elapsed time in the wrong box.
This page adds, subtracts and converts durations — lengths of time, like 2 hours 45 minutes. The hours-between-times calculator works out the elapsed time between two clock times, like 9:00 AM to 5:30 PM. Use this one for adding up hours worked or trained; use that one for the span between a start time and an end time.
Not directly: the inputs are whole minutes only, so a duration with seconds has to be rounded to minutes first. The total seconds are still shown — 4 hours 15 minutes is 15,300 seconds — and the decimal hours are printed to 6dp, so 255 minutes is 4.250000 decimal hours.