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Time Add & Subtract

Date & Time

Sum multiple durations · timecodes & splits · average

Quick Answer

Time Add & Subtract: Sum multiple durations · timecodes & splits · average. Time Add & Subtract uses standard date & time formulas to compute accurate results instantly.

Scene presets
Total of 4 durations
8:46:50
8h 46m 50s
Decimal hours8.781h
Total minutes526.83min
Total seconds31,610s
Average2:11:43
Longest3:45:20
Shortest0:58:35

How it adds up

  1. 1Parse each line into seconds (h:mm:ss / m:ss / 1h30m / plain seconds)
  2. 2Line 1: 3:45:20 → 13,520 s (+)
  3. 3Line 2: 1:52:10 → 6,730 s (+)
  4. 4Line 3: 58:35 → 3,515 s (+)
  5. 5Line 4: 2:10:45 → 7,845 s (+)
  6. 6Signed sum = 31,610 s
  7. 7Normalize back: 31,610 s → 8:46:50

Duration quick reference

UnitEquivalent
1 minute60 s
1 hour60 min = 3,600 s
1 day24 h = 86,400 s
Marathon 42.195Ksub-3 needs 4:16/km
Pomodoro25 min = 1,500 s
Standard workday8 h = 28,800 s
Two-part input like 45:20 reads as mm:ss (45 min 20 s); use three parts 1:45:20 for hours. A "−" line subtracts that duration — if subtractions exceed additions the total goes negative (shown with −). Typical uses: summing video timecodes, adding up running splits, weekly work-hour totals, playlist length.

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How to Use

  1. Pick dates or a mode: select start/end dates or switch modes in the Time Add & Subtract.
  2. Instant calculation: results appear immediately with day/week/month equivalents.
  3. Solve both ways: change any field and everything updates — forward or reverse.
  4. Check the context: read the solar-term/holiday/rule notes on this page.

Key Points

  • Time Add & Subtract is a free online date & time tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Sum multiple durations · timecodes & splits · average.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Time Add & Subtract formula

Time Add & Subtract uses standard date & time formulas to compute accurate results instantly.

FAQ

How do I use the Time Add & Subtract?
Open the page and fill in the input fields — results update automatically. Sum multiple durations · timecodes & splits · average.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on standard calendar arithmetic. Last updated: 2025-07

Authoritative sources:

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Time Add & Subtract[EB/OL]. https://www.yijiansuan.com/en/c/date/duration-sum

Results provided by this tool are for reference only and do not constitute professional advice.