How to add hours and minutes
Time is counted in base 60, not base 10. That is the only trick. Add the minutes together, add the hours together, then turn every 60 minutes into one more hour.
Take 1:30 + 2:45. The minutes give 30 + 45 = 75 minutes, which is 1 hour and 15 minutes. The hours give 1 + 2 = 3 hours. Add the extra hour: 4 hours and 15 minutes, written 4:15.
The calculator above does this for as many lines as you need, up to twelve. Each line can be added or subtracted, so you can take out a break or a correction without doing the math on the side.
| Calculation | Result | How it works |
|---|---|---|
| 1:30 + 2:45 | 4:15 | 75 minutes = 1:15, plus 3 hours |
| 0:50 + 0:40 + 0:35 | 2:05 | 125 minutes = 2 hours 5 minutes |
| 8:00 − 0:45 | 7:15 | borrow one hour: 7:60 − 0:45 |
| 3:10 − 1:25 | 1:45 | borrow one hour: 2:70 − 1:25 |
| 9:30 × 5 days | 47:30 | 570 minutes × 5 = 2,850 minutes |
How to subtract time
When the minutes you take away are larger than the minutes you have, borrow one hour and turn it into 60 minutes. For 3:10 − 1:25, rewrite 3:10 as 2:70. Then 70 − 25 = 45 minutes and 2 − 1 = 1 hour, so the answer is 1:45.
In the calculator, tap the sign in front of a line to switch it from + to −. A total can go below zero: 0:30 − 0:45 shows −0:15, which is handy to see how far you are from a target.
Time between two times
To find how long it is from one clock time to another, turn both into minutes since midnight and subtract. From 8:30 AM to 5:15 PM: 17 × 60 + 15 = 1,035 minutes, minus 8 × 60 + 30 = 510 minutes, which leaves 525 minutes, or 8 hours 45 minutes.
If the end time is earlier than the start time, the period runs past midnight. Add 24 hours to the end. A night shift from 10:00 PM to 6:30 AM lasts 8 hours 30 minutes. The calculator does it on its own and tells you the end falls on the next day.
For a full work week with breaks and overtime, the hours calculator adds up each day for you. For dates rather than times, use the date calculator.
Hours and minutes in decimal hours
Payroll software and invoices often want decimal hours: 7.75 instead of 7:45. Divide the minutes by 60 and keep the hours: 45 ÷ 60 = 0.75, so 7:45 is 7.75 hours. The total above is always shown both ways.
| Hours and minutes | Decimal hours | Minutes |
|---|---|---|
| 0:15 | 0.25 | 15 |
| 0:30 | 0.50 | 30 |
| 0:45 | 0.75 | 45 |
| 1:20 | 1.33 | 80 |
| 7:30 | 7.50 | 450 |
| 8:45 | 8.75 | 525 |
The decimal hours converter has the full table for every minute from 1 to 59, and converts in both directions.
Two shortcuts for mental math
Round up, then take back. Adding 2:45 is the same as adding 3:00 and removing 15 minutes. So 1:30 + 2:45 = 4:30 − 0:15 = 4:15. It works well with values like 0:50, 1:55 or 7:45, which sit just under a round hour.
Count short durations in minutes. For a list of short tasks, add the minutes first: 50 + 40 + 35 = 125 minutes, then split into hours: 120 minutes is 2 hours, so 2:05. Below two or three hours, it is usually faster than juggling hours and minutes.
Hours and minutes at a glance
| Period | Hours | Minutes |
|---|---|---|
| 1 day | 24 | 1,440 |
| 1 week | 168 | 10,080 |
| Work week of 40 hours | 40 | 2,400 |
| 40 hours × 52 weeks | 2,080 | 124,800 |
| Year of 365 days | 8,760 | 525,600 |
| Leap year (366 days) | 8,784 | 527,040 |
The 2,080 figure is the usual number of paid hours in a full-time year in the United States. Divide a yearly salary by 2,080 to get a rough hourly rate.
Everyday uses
- Timesheets. Add the hours of each task or each day, and subtract the unpaid breaks.
- Projects and freelancing. Total the time spent on a client before you send the invoice.
- Video and audio. Add the length of clips or tracks to check that a playlist or an edit fits.
- Travel. Add up flight legs and layovers to know the total trip time.
- Training. Total your weekly running or cycling time. To measure a session live, use the stopwatch.
- Sleep. Count the hours between bedtime and the alarm, or let the sleep calculator suggest a bedtime.
Common mistakes
- Reading 1.30 as 1:30. 1.30 decimal hours is 1 hour 18 minutes, not 1 hour 30. Keep the colon for hours and minutes, and the point for decimals.
- Mixing up AM and PM. 12:00 PM is noon and 12:00 AM is midnight. A 12-hour mix-up adds or removes exactly 12 hours.
- Forgetting midnight. 11:00 PM to 2:00 AM is 3 hours, not 21. The end is on the next day.
- Daylight saving time. On the night the clocks change, a shift really lasts one hour more or one hour less than the clock times suggest. The calculator counts clock time, so adjust by hand on those two nights.
- Spreadsheets. In Excel or Google Sheets, a sum of times over 24 hours wraps around unless the cell uses the [h]:mm format.