Time Calculator

Add or subtract time, duration between times, and convert decimal hours to HH:MM:SS.

Result

Fill in the fields above, then press Calculate.

A time calculator adds, subtracts, or finds the duration between two times, and converts between decimal hours and HH:MM:SS format.

Select an operation: add two durations, subtract durations, find the time between two clock times, or convert decimal hours to HH:MM:SS. Enter the values as prompted. Click Calculate. Useful for timesheets and scheduling.

Examples

Add Two Durations

2 hours 45 minutes + 1 hour 30 minutes = 4 hours 15 minutes (total 255 minutes or 15,300 seconds).

Time Between Events

From 9:15 AM to 5:45 PM is 8 hours 30 minutes, useful for calculating work shift length.

Frequently Asked Questions

How do I convert decimal hours to HH:MM?
Multiply the decimal part by 60 to get minutes. For example, 7.75 hours = 7 hours and 0.75 × 60 = 45 minutes, so 7:45.
Can I calculate overnight durations?
Yes. If the end time is earlier than the start time, the calculator assumes the duration crosses midnight. For example, 10:00 PM to 6:00 AM = 8 hours.
Related Calculators
Hours Calculator
Time Duration Calculator
Time Card Calculator
Time Zone Calculator

Quick Tips

  • •Remember that months have different lengths — calculations account for 28-31 day months automatically.
  • •Use the decimal-to-HH:MM converter when filling out timesheets that require one format or the other.
  • •For overnight shifts, the calculator automatically adds 24 hours when the end time is before the start time.