Hours between two times
The time duration calculator finds how long it is from a start time to an end time, in hours and minutes and in decimal hours. If the end time is earlier than the start time, it assumes the period crosses midnight, as for a night shift. You can also take off an unpaid break.
The formulas
- Duration = end time − start time, plus 24 hours if the result is negative
- Worked time = duration − break
- Decimal hours = hours + minutes ÷ 60
Worked example
A shift from 9:00 AM to 5:30 PM with a 30-minute lunch:
- 5:30 PM − 9:00 AM = 8 hours 30 minutes.
- Minus the break: 8 hours worked.
- In decimal hours: 8.00, or 480 minutes.
For a night shift from 10:00 PM to 6:30 AM, the end time is earlier than the start, so the calculator adds 24 hours: 6:30 + 24:00 − 22:00 = 8 hours 30 minutes.
Minutes to decimal hours
| Minutes | Decimal |
|---|---|
| 6 | 0.10 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 40 | 0.67 |
| 45 | 0.75 |
Breaks and paid time
Under US federal rules, short rest breaks, usually 5 to 20 minutes, count as hours worked and must be paid. Meal periods of at least 30 minutes, during which the employee is fully relieved from duty, can be unpaid. Several states, including California, require meal and rest breaks by law; others leave it to the employer.
Tips for accurate time tracking
- Record times to the minute rather than rounding in your head; rounding rules, if any, should be set by the employer and applied evenly.
- Use 24-hour time or note AM and PM clearly, since the most common error is a PM end time typed as AM.
- For several days, the time card calculator adds up a full week and computes overtime.
Beyond work
The same calculation answers everyday questions: how long a flight lasts between departure and arrival in the same time zone, how long you slept, or how long a game, a film or a recording runs between two timestamps.