Time Calculator

Add, subtract, and convert time units

About Time Calculator

A time calculator adds, subtracts, or converts time values — hours, minutes, and seconds — and can also find the duration between two times of day. It's used for scheduling, timesheets, cooking, workouts, and any calculation involving elapsed or combined time.

Formula

Total Time = Hours + (Minutes / 60) + (Seconds / 3600), converted back to hh:mm:ss format

How It Works

Choose to add/subtract time durations, or find the difference between two clock times
Enter values in hours, minutes, and seconds
The calculator converts everything to a common unit (like total seconds), performs the calculation, then converts back to hh:mm:ss
For time-of-day differences, it accounts for crossing midnight if needed

Tips

When adding times, minutes and seconds that exceed 60 automatically carry over into the next larger unit
For time-of-day calculations spanning midnight (e.g., 10 PM to 2 AM), the calculator adds 24 hours to the later time before subtracting
Converting between decimal hours (e.g., 2.5 hours) and hh:mm format (2 hours 30 minutes) is a common source of timesheet errors — 0.5 hours is 30 minutes, not 50 minutes

Frequently Asked Questions

How do I add two time durations together?

Convert each duration to total seconds (or minutes), add them together, then convert the sum back into hours, minutes, and seconds, carrying over any values of 60 or more into the next unit.

How do I calculate the time between two clock times?

Subtract the earlier time from the later time; if the calculation spans midnight (end time is earlier in the day than start time), add 24 hours to the end time before subtracting.

How do I convert decimal hours to minutes?

Multiply the decimal portion by 60. For example, 2.75 hours = 2 hours + (0.75 × 60) minutes = 2 hours 45 minutes.

Why does my timesheet show 2.5 hours instead of 2 hours 50 minutes?

Decimal time formats express minutes as a fraction of an hour, so 0.5 hours equals 30 minutes, not 50 — always convert carefully between decimal and hh:mm formats to avoid payroll errors.

How many seconds are in a given number of hours?

Multiply hours by 3,600 (60 minutes × 60 seconds). For example, 3 hours = 10,800 seconds.