Time Calculator - Add & Subtract Hours and Minutes

Time Durations

Add and subtract hours, minutes and seconds, total a list of durations and convert to decimal hours. Free, with multiple rows and export.

Add time entries

Choose operation

Review total

Or fill a time card

This adds and subtracts the entries as typed. Check AM and PM on a time card and the operator on each row before using the total for payroll or billing.

Formulas and sources

Each formula this calculator uses, where it comes from, and what it leaves out. "How it works" shows the same formula with your own numbers.

Total of the durations

Durations mode

Total seconds = sum of all (hours × 3600 + minutes × 60 + seconds)
Total seconds
every row in seconds, added or subtracted by its + or − operator

The total is shown in hours, minutes and seconds, and in decimal hours, the seconds ÷ 3,600. A row whose field shows an error, such as a clock time typed into Hours, is left out.

Source: Uses NIST's exact factors: an hour is 3,600 seconds and a minute is 60 [1].

Worked time on a time card

Time Card mode

Worked = clock-out − clock-in − break, summed over every shift
Worked
the time worked across every shift

When the clock-out is earlier than the clock-in, the shift ends the next day and 24 hours are added. The break is in minutes, and a shift never counts below zero.

Source: Standard formula; no single publisher. The overnight rule is CalcTrail's own.

8h Workdays and Average Shift

Durations and Time Card modes

8h Workdays, in Durations, is the total ÷ 8 hours. Average Shift, on a Time Card, is the total ÷ the number of shifts with time worked.

Source: CalcTrail's own measures; no publisher.

Sources

  1. National Institute of Standards and Technology. NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, day, hour and minute. Special Publication 811, 2008 edition.

What this calculator does not cover

  • It works in hours, minutes and seconds, and on a Time Card in clock times. For dates or time zones, see the Date Difference Calculator and the Time Zone Converter.
  • It does not adjust for the hour skipped or repeated on the night clocks change.
  • It does not work out overtime or pay. The Time Card Calculator does.

Sources checked on .

Help

Quick Start Guide

  1. Add time entries: Enter hours, minutes, and seconds.
  2. Choose operation: Set + or - on each row after the first; the first row always adds.
  3. Review total: See the combined duration instantly.
  4. Or fill a time card: Switch to Time Card and enter a clock-in, clock-out and unpaid break for each shift.

Frequently Asked Questions

Switch the Mode toggle to Time Card. Each shift row takes a clock-in, a clock-out, an unpaid break in minutes, and an optional day label; the worked time for that row shows as you type, and the panel totals every shift in hours, minutes and seconds and in payroll decimal hours. A clock-out earlier than the clock-in is treated as an overnight shift: 22:00 to 06:00 is eight hours. A clock-out equal to the clock-in counts as zero and is flagged, so enter a 24-hour shift as two rows. The card counts clock time: on the night the clocks change, an overnight shift is an hour longer or shorter than it shows. For pay, weekly or daily overtime and punch rounding, use the Time Card Calculator: Continue in another calculator sends these shifts there. Label each row with its weekday (Mon, Tue) and up to two weeks arrive on their own days, the card starting on the first shift’s day; without weekday labels, up to seven shifts arrive one day each. Rows with the same label, one after another, arrive as one day’s split shift, up to three shifts a day. Longer lists are not offered: the card holds two weeks, and past seven unlabeled shifts it could not tell which week each belongs to.

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