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Time Duration Calculator

Add/subtract durations and times.

beats calculator.net edge: List sum + clock-time subtraction
durations · sum
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Guide

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.

What a time duration calculator does

A duration calculator answers two questions: how long between two times and what is the total of these durations. Both are error-prone by hand — carrying across the 60-second and 60-minute boundaries, crossing midnight, and summing a long list. This tool converts every value to seconds, does the math exactly, and formats it back to HH:MM:SS.

It handles the cases people actually hit:

  • Between two times — 09:30 – 17:45 → 8h 15m, including overnight spans (22:00 – 02:00 = 4h).
  • With breaks / lunch — subtract the unpaid break to get paid hours.
  • Military (24-hour) time — enter 14:00, 22:30 directly.
  • Sum a list — one duration per line, get the total (podcast playlists, billable entries).
  • Beyond 24 hours — 48:30:00 is valid.

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.
What is a time duration calculator and how does it work?
It computes the length of time between two clock times, or the total of several durations, in hours/minutes/seconds. Internally it converts each time to total seconds, does the arithmetic, and formats the result back to HH:MM:SS — which correctly handles crossing midnight and totals beyond 24 hours.
How do I subtract a lunch or break from a shift?
Compute the shift span first (e.g. 09:00 - 17:30 = 8h 30m), then subtract the break as its own duration (8:30 - 0:30 = 8h 00m). Enter the break with a minus sign, or list it and use the sum view. This is the standard way to get paid hours from clock-in/clock-out with an unpaid lunch.
Does it work with military (24-hour) time?
Yes — enter times in 24-hour form (14:00, 22:30) and the calculator treats them as military time directly. It also handles wrap-around, so 22:00 - 02:00 correctly returns 4 hours across midnight.

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Last updated: 2026-07-04