Time Calculator
Add or subtract two durations in hours, minutes, and seconds — and see the result converted into each unit.
How to add and subtract time
total seconds = h×3600 + m×60 + s
1h 45m + 0h 30m = 6,300s + 1,800s = 8,100s = 2h 15m (2.25 hours or 135 minutes).
When to use this vs. the hours calculator
This tool adds and subtracts durations — total up lap times, combine task estimates, or find the difference between two lengths of time. If instead you want the hours worked between a clock-in and clock-out (minus lunch), the hours calculator is built for that. For calendar spans in days, use the date calculator. Note that subtracting a larger time from a smaller one gives a negative duration, shown here as a signed result.
Frequently asked questions
How do I add hours and minutes together?
Add each unit and carry: 60 seconds → a minute, 60 minutes → an hour. 1h45m + 30m = 2h15m.
How do I convert minutes to hours?
Divide by 60. 90 minutes = 1.5 hours.
How is this different from the hours calculator?
This adds/subtracts durations; the hours calculator finds time worked between clock-in and clock-out.
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Last reviewed: July 2026.