Common shift lengths on a 24-hour clock

Each bar shows where a common shift sits in the day, with its exact length. Select a shift to load it into the calculator.

How many hours are between two times?

A lunch break is what usually separates clock time from paid time. 7:00 AM to 3:30 PM is 8 hours 30 minutes on the clock, but a 30-minute unpaid lunch leaves 8.00 paid hours.

Start	End	Unpaid break	Duration	Minutes	Decimal hours
8:30 AM	5:00 PM	None	8 h 30 m	510	8.50
7:00 AM	3:30 PM	30 min	8 h 0 m	480	8.00
8:45 AM	5:15 PM	45 min	7 h 45 m	465	7.75
11:00 AM	7:20 PM	None	8 h 20 m	500	8.33
7:00 PM	7:00 AM	60 min	11 h 0 m, overnight	660	11.00
12:00 PM	12:00 AM	None	12 h 0 m, overnight	720	12.00

The last row runs from noon to the midnight that ends the day, which a 12-hour clock writes as 12:00 PM to 12:00 AM. Decimal hours are the minutes divided by 60, rounded to 2 places, which is why 20 minutes shows as 0.33. The minutes-to-decimal chart lists all 60 values.

A week of shifts is quicker on the weekly time card, which adds the days, rounds punches if you choose and splits off overtime past 40 hours.

Subtracting two times by hand

Take 8:45 AM to 5:20 PM. On the 24-hour clock that is 08:45 to 17:20, and the minutes column is worked first, borrowing 60 minutes when it runs short.

Step	Working	Result
1. Switch to the 24-hour clock	8:45 AM → 08:45, 5:20 PM → 17:20	08:45 and 17:20
2. Borrow 1 hour, since 20 is less than 45	17:20 → 16:80	16:80
3. Subtract minutes, then hours	80 − 45 = 35 m, 16 − 8 = 8 h	8 h 35 m
4. Convert to decimal	35 ÷ 60 = 0.58	8.58 hours

The span is 515 minutes, or 30,900 seconds. In Excel or Google Sheets, =MOD(B2-A2,1)*24 returns decimal hours for a start time in A2 and an end time in B2. A spreadsheet counts one day as 1, so MOD repairs an end that falls after midnight, and × 24 turns the fraction of a day into hours. The guide to subtracting times by hand works through overnight shifts, borrowing shortcuts and common mistakes.

What if the end time is earlier than the start time?

Then the span crosses midnight, and the end belongs to the next day. Split it at midnight: 9:30 PM to 12:00 AM is 2 hours 30 minutes, and 12:00 AM to 5:15 AM adds 5 hours 15 minutes. The shift lasts 7 hours 45 minutes, or 7.75 hours.

Clock times mode makes that assumption on its own and labels the result overnight. A span over two or more nights needs Dates and times with the real dates.

How the time duration calculator handles more than 24 hours

Dates and times mode keeps counting in hours past 24. Friday 6:00 PM to Sunday 2:30 AM totals 32 hours 30 minutes, which the result also writes as 1 day, 8 h 30 m.

When you know the start and the length instead of the end, hours from now gives the end time and date, and counting hours back finds a start from an end.

Does daylight saving time change a duration?

Yes, if the span crosses a clock change: real elapsed time runs 1 hour short in March and 1 hour over in November, compared with the clock difference. The spring-forward night skips an hour, and the fall-back night repeats one.

Range (New York time)	Clock difference	Real elapsed time
March 7, 2026, 10:00 PM to March 8, 2026, 6:00 AM	8 hours	7 hours
November 1, 2026, 12:00 AM to 3:00 AM	3 hours	4 hours

Dates and times mode reads your device’s time zone, finds the change and names it under the result. Clock times mode compares the two readings only, the way most timesheets record a shift. This year’s clock change dates have their own countdown.

Frequently asked questions

Why does 7:00 AM to 7:00 AM show 0 hours?

Clock times reads a start and end that match as no time at all. For a 24-hour shift, switch to Dates and times and give the end the next day's date.

Should I enter a paid break?

No. The break box is for unpaid time, such as a 30-minute lunch. A paid break is part of the time you are paid for, so it stays in the duration.

Why is 8 hours 30 minutes written as 8.50 and not 8.30?

Decimal hours count fractions of an hour, and 30 minutes is half an hour, so it becomes 0.50. Read as decimal hours, 8.30 would mean 8 hours 18 minutes.