Free Online Calculators
Add and subtract hours, minutes and seconds, time between two times, military time
To add times, convert hours and minutes to seconds, add, and convert back: 2:45:30 + 1:30:45 − 0:20:00 = 3:56:15. The time from 9:30 PM to 6:15 AM is 8 hours 45 minutes. 45 minutes are 0.75 hours, and 7:45 PM is 19:45 or 1945 in military time.
45 minutes are 0.75 hours. To add or subtract times, convert them to seconds or minutes, calculate, and convert back: 2:45:30 + 1:30:45 − 0:20:00 = 3:56:15. From 9:30 PM to 6:15 AM are 8 hours 45 minutes, and 7:45 PM is 1945 in military time.
| Minutes | Decimal hours | Seconds |
|---|---|---|
| 5 minutes | 0.0833 | 300 |
| 6 minutes | 0.1 | 360 |
| 10 minutes | 0.1667 | 600 |
| 12 minutes | 0.2 | 720 |
| 15 minutes | 0.25 | 900 |
| 18 minutes | 0.3 | 1,080 |
| 20 minutes | 0.3333 | 1,200 |
| 24 minutes | 0.4 | 1,440 |
| 25 minutes | 0.4167 | 1,500 |
| 30 minutes | 0.5 | 1,800 |
| 35 minutes | 0.5833 | 2,100 |
| 36 minutes | 0.6 | 2,160 |
| 40 minutes | 0.6667 | 2,400 |
| 42 minutes | 0.7 | 2,520 |
| 45 minutes | 0.75 | 2,700 |
| 48 minutes | 0.8 | 2,880 |
| 50 minutes | 0.8333 | 3,000 |
| 54 minutes | 0.9 | 3,240 |
| 55 minutes | 0.9167 | 3,300 |
| 60 minutes | 1 | 3,600 |
Add the minutes and the hours separately, then turn every 60 minutes into one hour. 2 h 45 min + 1 h 30 min = 3 h 75 min = 4 h 15 min.
Subtract the start time from the end time. If the end is earlier than the start, add 24 hours because the period crosses midnight: 9:30 PM to 6:15 AM are 8 hours 45 minutes.
Divide the minutes by 60. 15 minutes are 0.25 hours, 30 minutes 0.5 hours and 45 minutes 0.75 hours, so 7 hours 45 minutes are 7.75 hours.
Add 10 hours to the current time and subtract 24 if the result passes midnight. 2:40 PM plus 10 hours is 12:40 AM the next day.
For times after noon add 12 to the hour and drop the colon: 7:45 PM is 1945. Midnight is 0000 and 12:30 AM is 0030.
Time does not add up like ordinary decimals, because 60 seconds make a minute and 60 minutes make an hour. The easiest way is to convert every entry into seconds, add or subtract, and convert back. The calculator does exactly that for as many rows as you need: 2:45:30 plus 1:30:45 minus 0:20:00 is 3:56:15, or 3.9375 hours. Totals above 24 hours are shown as hours and additionally as days, which is useful for adding up shifts, study sessions, video lengths or workout logs.
To find the duration between a start and an end time, subtract the start from the end. If the end time is earlier than the start time, the period runs past midnight, and the calculator counts the end on the next day. From 9:30 PM to 6:15 AM are 8 hours and 45 minutes. Enter an unpaid break in minutes to get the net time, for example for a night shift.
The third mode answers questions like “what time will it be in 10 hours and 35 minutes?”. Add the duration to the clock time and wrap around at midnight. 2:40 PM plus 10 hours 35 minutes is 1:15 AM the next day. Subtracting works the same way, for example to find when to start cooking or leave for the airport.
Timesheets and payroll systems often want decimal hours. Divide the minutes by 60: 15 minutes are 0.25 hours, 30 minutes 0.5 hours and 45 minutes 0.75 hours. So 7 hours and 45 minutes are 7.75 hours. The table on this page lists the common values.
The 24-hour clock counts the hours of the day from 00 to 23, so 7:45 PM is 19:45. Military time writes the same value with four digits and no colon, 1945, and says it as “nineteen forty-five hours”. Midnight is 0000 and noon is 1200. For hours after noon, add 12 to the 12-hour value; for 12 AM subtract 12. The last mode converts any time into all three formats.
To count the hours of a work week with clock-in, clock-out and breaks, use the work hours calculator. To count days between two dates, use the days between dates calculator.