Time Calculator

Start with elapsed clock time. Switch calculation type for duration arithmetic, expression parsing, or calendar-date math; the form shows only the fields that mode needs.

Elapsed compares start/end. Add/subtract uses the start time and duration fields. Expression evaluates a duration string. Date add/subtract works on calendar dates.
Use local 24-hour input, such as 09:15 for 9:15 AM.
Elapsed-time mode only. Leave as-is when adding or subtracting a duration.
Add/subtract and date-arithmetic modes only. Whole hours.
Add/subtract and date-arithmetic modes only. Minutes can exceed 59; the calculator normalizes.
Expression mode only. Tokens like 2h, 15m, 30s, 1d separated by + or −.
Date arithmetic modes only. Use YYYY-MM-DD.
Date arithmetic modes only. Whole days to add or subtract.
Advanced options
Elapsed-time mode only. Decide how to handle an end time earlier than the start.
Add/subtract and date-arithmetic modes only. Whole seconds for precise arithmetic.
Answer 8 hr 30 min
Duration 8 hr 30 min
Show calculation details
Decimal hours 8.50 h
Total minutes 510.00 min
Clock result 5:45 PM · same day