About Time Duration Calculator
HH:MM:SS arithmetic. Sum a list of durations (one per line), subtract two clock times, convert between HH:MM:SS and total seconds. Useful for billable hours, video / audio duration sums, shift planning, and meeting math.
Common workflows
Total a podcast playlist. Paste durations (one per line), get total. “12 episodes, 14h 23m total.”
Bill a freelance day. Sum your time entries: 1:30 + 0:45 + 2:15 = 4h 30m.
Shift overlap. “I worked 14:00-22:00, you worked 18:00-02:00. Overlap?” → 4 hours.
Meeting math. Stand-up 0:15 + design review 0:45 + 1-on-1 0:30 = 1h 30m of meetings today.
Budget remaining. Total budget 8h, spent 5h 23m → 2h 37m remaining.
Frequently asked questions
Subtract clock times?
Yes — enter "09:30 - 17:45", get 8h 15m. The tool handles day boundaries (22:00 → 02:00 = 4h).
Sum a list of durations?
Paste a list (one per line, HH:MM:SS or MM:SS or seconds), get the total. Useful for podcast / video series total time.
Convert to total seconds?
Yes — both ways. 1:30:45 → 5,445 seconds.
Negative durations?
Yes — prefix with "-". Useful when reporting "running this much under budget".
Beyond 24 hours?
Yes. The format extends naturally — "48:30:00" is 48 hours 30 minutes.
Round to minutes?
Toggle to round seconds up to the nearest minute (common in timesheet contexts).
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Last updated: 2025-01-15