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Time Calculator
Add or subtract hours, minutes and seconds, or add time to a clock time to find when something ends.
Calculated in your browser – nothing you enter is sent or stored.
This time calculator adds and subtracts time in days, hours, minutes and seconds, adds a duration to a date and time of day to find when something ends, and converts between hours, minutes and seconds. Every result is shown as hh:mm:ss, decimal hours and total minutes and seconds.
How to Use the Time Calculator
- Add or subtract time: enter two durations, choose + or −, and read the total. Use it for video lengths, race splits, cooking times or work hours.
- From a date and time: enter a start date and clock time, then the hours and minutes to add or subtract. The result shows the end time and whether it falls on a later day.
- Convert a time: turn 2.75 hours into 2 hours 45 minutes, or 150 minutes into 2.5 hours.
To find the time between two clock times, such as a work shift, use the hours calculator. For days between two dates, use the date calculator.
How to Add Time by Hand
- Line up hours, minutes and seconds and add each column.
- If seconds reach 60 or more, subtract 60 and carry 1 to the minutes. Do the same with minutes into hours.
Example: 2 h 45 min 0 s + 1 h 30 min 15 s = 3 h 75 min 15 s. 75 minutes is 1 hour 15 minutes, so the total is 4 h 15 min 15 s – 4.2542 decimal hours or 255.25 minutes.
To subtract, borrow 60 when the column on top is smaller: 5 h 10 min − 2 h 35 min becomes 4 h 70 min − 2 h 35 min = 2 h 35 min.
Converting Minutes to Decimal Hours
Timesheets and payroll often use decimal hours. Divide the minutes by 60: 45 minutes = 0.75 hours, so 7 h 45 min is 7.75 hours.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.08 | 35 | 0.58 |
| 10 | 0.17 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 25 | 0.42 | 55 | 0.92 |
| 30 | 0.50 | 60 | 1.00 |
To go the other way, multiply the decimal part by 60: 3.4 hours = 3 hours + 0.4 × 60 = 3 hours 24 minutes.
Useful Time Facts
- 1 day = 24 hours = 1,440 minutes = 86,400 seconds.
- 1 week = 168 hours = 10,080 minutes.
- A 365-day year has 8,760 hours; a leap year has 8,784.
- The 24-hour clock (military time) runs from 00:00 to 23:59: 1:00 PM is 13:00 and 11:30 PM is 23:30.
Adding hours to a clock time can cross a daylight saving change. The calculator uses your device's clock and time zone, so a result that crosses the change in March or November reflects it.
Sources
- NIST – Time and frequency division
- U.S. Department of Labor – Fact sheet #21: Recordkeeping requirements under the FLSA
- time.gov – Official U.S. time
Last reviewed: October 2026 by the ShrinkBee team. Results are estimates for planning and education, not financial, tax, legal or medical advice.
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