Time Calculator
Add and subtract time durations, or convert between seconds, minutes, hours, and days.
Add / Subtract time
Convert units
Enter values and click Calculate.
How to use this calculator
- Choose 'Add / Subtract time' to combine or compare two time durations.
- Enter each time in HH:MM:SS format (e.g. 01:30:00 for 1 hour 30 minutes).
- Choose Add or Subtract, then click Calculate.
- Switch to 'Convert units' to convert a value between seconds, minutes, hours, and days.
- Enter a number, choose from-unit and to-unit, then click Calculate.
When people use this
- Adding up work hours across multiple shifts.
- Subtracting a film runtime from a booked time slot.
- Converting race times: minutes per km to total seconds.
- Working out how many hours are in a multi-day project window.
Examples
- 01:30:00 + 00:45:30 = 2 h 15 m 30 s (8,130 s total)
- 02:00:00 − 00:45:00 = 1 h 15 m 0 s
- 120 min → 2 hr (factor: 0.0167 hr/min)
- 3 days → 259,200 seconds
FAQ
What format should I use for the add/subtract mode?Use HH:MM:SS — two digits each, colon-separated. For example 01:05:30 means 1 hour 5 minutes 30 seconds.
Can I add times that total more than 24 hours?Yes — the result is shown in total hours, minutes, and seconds regardless of day boundaries.
What happens if the result is negative?The calculator warns you — subtract a smaller time from a larger one to get a valid result.
How accurate are the conversions?Conversions use exact factor values: 1 min = 60 s, 1 hr = 60 min, 1 day = 24 hr.
Can I use decimal values in convert mode?Yes — decimal inputs are supported, e.g. 1.5 hours.