The gap between two clock times is simple arithmetic until the span crosses midnight, at which point subtracting one from the other produces a negative number. This calculator works in minutes past midnight and adds a full day when the end time is earlier, so 09:15 to 17:45 returns 8h 30m and 22:30 to 06:15 returns 7h 45m rather than a negative figure.
Both figures matter in different places. Rotas and shift patterns are quoted in hours and minutes, while payroll and invoicing systems almost always want decimal hours, and the conversion between them is where mistakes creep in — 8 hours 30 minutes is 8.5, not 8.30. The result is given both ways so nothing has to be converted by hand.
The midpoint is included because it answers a question people usually work out separately: when the halfway mark of a shift, an exam or a journey actually falls. It is the start time plus half the duration, wrapped around midnight if the span crosses into the next day.
The formula
S- Start time, minutes past midnight
E- End time, minutes past midnight
D- Elapsed minutes
H- Elapsed hours in decimal form
How it works, step by step
- Enter the start time in 24-hour HH:MM form.
- Enter the end time the same way.
- Choose whether a span that ends earlier should roll into the next day.
- Read the duration in hours and minutes, in decimal hours and as a share of a full day.
Worked examples
09:15 to 17:45
The difference is 510 minutes, which is 8h 30m or 8.50 decimal hours. That is 35.4% of a 24-hour day, and the midpoint falls at 13:30.
A night shift from 22:30 to 06:15
Plain subtraction gives -975 minutes, which is meaningless. Adding a full day of 1440 minutes gives 465 minutes, or 7h 45m, with the midpoint at 02:22.
How to read your score
Frequently asked questions
Why is 8 hours 30 minutes not 8.30 in decimal?
Because minutes are sixtieths, not hundredths. Thirty minutes is 30 ÷ 60 = 0.5 of an hour, so the decimal form is 8.5. Treating 8.30 as the decimal understates the time by 12 minutes.
How does the calculator handle a span across midnight?
It adds 1440 minutes — one full day — when the end time is earlier than the start. A shift from 22:30 to 06:15 therefore returns 7h 45m rather than a negative number.
Does it subtract breaks?
No. This page measures raw elapsed time between two clock readings. If you need paid hours after an unpaid break, use the break-adjusted hours calculator instead.
Can I enter times with am and pm?
Yes. The parser accepts 9:15 am and 5:45 pm as well as the 24-hour forms, and rejects impossible values such as 25:00 or 09:75 rather than guessing at what was meant.
Elapsed time reference
| Start | End | Duration | Decimal hours | Minutes |
|---|---|---|---|---|
| 09:00 | 17:00 | 8h 00m | 8.00 | 480 |
| 09:15 | 17:45 | 8h 30m | 8.50 | 510 |
| 08:30 | 16:00 | 7h 30m | 7.50 | 450 |
| 07:00 | 15:30 | 8h 30m | 8.50 | 510 |
| 13:45 | 18:20 | 4h 35m | 4.58 | 275 |
| 22:30 | 06:15 | 7h 45m | 7.75 | 465 |
| 20:00 | 04:00 | 8h 00m | 8.00 | 480 |
The last two rows cross midnight, so a full day of 1440 minutes has been added.