Add up or subtract any number of times in hours, minutes and seconds, and see the total as h:mm:ss, decimal hours, minutes and days. The second calculator adds or subtracts hours and minutes from a clock time, across midnight.
3:55:00 (h:mm:ss)
- In words
- 3 hours 55 minutes
- Decimal hours
- 3.9167
- Total minutes
- 235
- Total seconds
- 14,100
- Days and hours
- 3:55:00 (under a day)
2:45:00 + 1:30:00 − 0:20:00 = 3:55:00
5:30 PM (17:30)
9:00 AM + 8 hours 30 minutes = 5:30 PM the same day.
How it’s calculated
Turn every time into seconds (hours × 3,600 + minutes × 60 + seconds), add or subtract them, then convert the total back: hours = total ÷ 3,600, minutes = the remainder ÷ 60. Decimal hours = total seconds ÷ 3,600.
For a clock time, add the minutes to the start time and wrap around 24 hours; every 24 hours is one day later (or earlier).
Worked example with your numbers
- 2:45:00 = 9,900 s; 1:30:00 = 5,400 s; 0:20:00 = 1,200 s.
- 9,900 + 5,400 − 1,200 = 14,100 seconds.
- 14,100 ÷ 3,600 = 3 hours, remainder 3,300 s = 55 minutes → 3:55:00 = 3.9167 hours.
Frequently asked questions
How do you add hours and minutes?
Add the minutes; every 60 minutes carry 1 hour. Then add the hours. 2:45 + 1:30 = 3 hours 75 minutes = 4:15.
How do you subtract time?
Turn both times into minutes (hours × 60 + minutes), subtract, and turn the result back into hours and minutes. 3:10 − 1:45 = 190 − 105 = 85 minutes = 1:25.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add the hours: 3:55 = 3 + 55 ÷ 60 = 3.9167 hours. Payroll uses decimal hours to multiply by the hourly rate.
What time will it be in 8 hours?
Use the clock time calculator: enter the start time and add 8 hours. If the result passes midnight, it shows that the time is on the next day.