How to calculate time
Here it is with your numbers:
- Turn the first time into minutes: 6 × 60 + 45 = 405 minutes.
- Turn the second time into minutes: 9 × 60 + 30 = 570 minutes.
- Add them: 405 + 570 = 975 minutes.
- Turn it back into hours: 975 ÷ 60 is 16 hours with 15 minutes left over, so 16 h 15 min.
It means 6 h 45 min plus 9 h 30 min is 16 h 15 min, or 16.25 hours as a decimal.
Minutes and seconds over 60 are fine: 90 minutes is read as 1 hour 30 minutes. To take time away, choose Subtract; if the second time is longer, the answer is negative.
Source Microsoft Support · Add or subtract time in Excel ↗
How to calculate the time between two times
Write both clock times as minutes after midnight and subtract. When the end time is earlier in the day than the start, it is on the next day, so add 24 hours (1,440 minutes) to the end first. A night shift from 10:00 PM to 6:30 AM: 10:00 PM is 1,320 minutes after midnight and 6:30 AM is 390, so the end becomes 390 + 1,440 = 1,830, and 1,830 − 1,320 is 510 minutes, which is 8 h 30 min.
Midnight is 12:00 AM, the start of the day, and noon is 12:00 PM. With no AM or PM, a time like 9 to 5 is read as 9 AM to 5 PM, the same as our Time Card Calculator.
Source Microsoft Support · Calculate the difference between two times in Excel ↗NIST Time and Frequency Division · Times of Day FAQs (noon and midnight) ↗
Time calculator examples
| Question | Answer |
|---|---|
| 6 h 45 min + 9 h 30 min | 16 h 15 min |
| 12 h 45 min + 15 h 30 min | 28 h 15 min |
| 8 h − 2 h 20 min | 5 h 40 min |
| 10:35 AM to 3:30 PM | 4 h 55 min |
| 10:00 PM to 6:30 AM | 8 h 30 min |
FAQs
How do I calculate hours and minutes?
Add the minutes, then the hours, and carry every 60 minutes into an hour. 6 h 45 min plus 9 h 30 min: 45 + 30 is 75 minutes, which is 1 hour 15 minutes, so the total is 16 h 15 min.
How many hours is 7:30 to 4:30?
From 7:30 AM to 4:30 PM is 9 hours. Write both as minutes after midnight (450 and 990) and subtract: 540 minutes, which is 9 hours.
Source Microsoft Support · Calculate the difference between two times in Excel ↗
How many hours is 9:45 to 2:30?
From 9:45 AM to 2:30 PM is 4 hours 45 minutes (4.75 hours). From 9:45 PM to 2:30 AM the next day is the same length.
How many hours are there between midnight and noon?
12 hours. Midnight (12:00 AM) starts the day and noon (12:00 PM) is the middle of it, so midnight to midnight is 24 hours.
Source NIST Time and Frequency Division · Times of Day FAQs (noon and midnight) ↗
How can I calculate the total time between two times in Excel?
Put the start time in one cell and the end time in another, then subtract the start from the end (for example =C2-B2) and format the cell as h:mm. Microsoft’s example: 10:35 AM to 3:30 PM is 4:55, or 295 minutes.
Source Microsoft Support · Calculate the difference between two times in Excel ↗
Sources
- Microsoft Support: Add or subtract time in Excel
- Microsoft Support: Calculate the difference between two times in Excel
- NIST Time and Frequency Division: Times of Day FAQs (noon and midnight)