Two ways to use the Time Calculator
Add / subtract time: enter a start time, choose add or subtract, and enter the hours and minutes. The calculator shows the new time on the 24-hour and 12-hour clock and tells you if the result moves into the next or previous day. For example, 22:00 plus 5 hours 15 minutes is 03:15 the next day.
Time between two times: enter a start and an end time to get the duration in hours and minutes, decimal hours and total minutes. If the end time is earlier than the start time, it is treated as the next day — 22:00 to 06:30 is 8 hours 30 minutes.
How to add and subtract time by hand
- Add (or subtract) the hours and the minutes separately.
- If the minutes reach 60 or more, take away 60 and add one hour. If they go below zero, add 60 and take away one hour.
- If the hours reach 24 or more, take away 24 — the time is on the next day. Below zero, add 24 — the time is on the previous day.
Example: 9:45 + 3 hours 30 minutes → 12 hours 75 minutes → 13:15 (1:15 PM).
Converting minutes and decimal hours
- To turn minutes into decimal hours, divide by 60: 45 minutes = 0.75 hours.
- To turn decimal hours into minutes, multiply the decimal part by 60: 2.4 hours = 2 hours 24 minutes.
- One day has 24 hours or 1,440 minutes; one week has 168 hours.
12-hour and 24-hour clock
The calculator uses the 24-hour clock for input (00:00 to 23:59) and shows results both ways. 00:00 is midnight (12:00 AM) and 12:00 is noon (12:00 PM); afternoon times are the 24-hour time minus 12, so 18:30 is 6:30 PM.
Related time and date tools
For work shifts with breaks, use the Hours Calculator. To include dates as well as times, use the Time and Date Calculator, and for whole days between two dates, the Date to Date Calculator.