Time Calculator
Add or subtract hours, minutes and seconds, find the clock time a number of hours from a given time, or the time between two clock times, also past midnight.
First time
Second time
2:45:30 + 1:30:45
4:16:15
4 hours 16 minutes 15 seconds
| First time2 hours 45 minutes 30 seconds | 2:45:30 |
|---|---|
| Second time1 hour 30 minutes 45 seconds | +1:30:45 |
| Result (h:mm:ss) | 4:16:15 |
| In decimal hours | 4.2708 |
| In minutes | 256.25 |
| In seconds | 15,375 |
How this is calculated
Time is counted in sixties: 60 seconds make a minute and 60 minutes make an hour. To add, add each column and carry every full 60 to the next one. 2:45:30 + 1:30:45: the seconds give 75, which is 1 minute and 15 seconds; the minutes give 45 + 30 + 1 = 76, which is 1 hour and 16 minutes; the hours give 2 + 1 + 1 = 4. The result is 4:16:15.
To subtract, borrow 60 when a column is too small: 3:15 − 1:45 becomes 2:75 − 1:45 = 1:30. A result below zero is shown with a minus sign.
A clock time plus hours wraps around at midnight: 9:30 AM plus 8 hours 30 minutes is 6:00 PM, and 10:00 PM plus 5 hours is 3:00 AM the next day. The calculator says how many days later or earlier the result falls.
The time between two clock times is the end minus the start. If the end is earlier than the start, it is on the next day and 24 hours are added: 9:15 AM to 5:45 PM is 8 hours 30 minutes; 10:00 PM to 6:30 AM is 8 hours 30 minutes. Clock times have no date, so the hour lost or gained when daylight saving time starts or ends is not counted.
12:00 AM is midnight at the start of a day and 12:00 PM is noon. In 24-hour time they are 00:00 and 12:00; 1:00 PM is 13:00.
Questions people ask
How do I add hours and minutes?
Add the minutes and the hours separately, then turn every 60 minutes into an hour. 2 h 45 min + 1 h 30 min = 3 h 75 min = 4 h 15 min.
What time will it be in 8 hours?
Add 8 to the hour and switch between AM and PM when you pass 12. 9:30 AM plus 8 hours is 5:30 PM; 10:00 PM plus 8 hours is 6:00 AM the next day.
How do I subtract time?
Subtract minutes from minutes and hours from hours, borrowing 60 minutes from the hours if needed. 3:15 − 1:45 = 2:75 − 1:45 = 1:30.
How do I find the time between two times across midnight?
Add 24 hours to the end time, then subtract the start. 10:00 PM to 6:30 AM is 30:30 − 22:00 = 8 hours 30 minutes.
Is 12:00 AM midnight or noon?
12:00 AM is midnight, the start of the day, and 12:00 PM is noon. In 24-hour time they are 00:00 and 12:00.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours. 4 hours 15 minutes is 4.25 hours; 2 hours 40 minutes is 2.67 hours.