Time Duration Calculator
The first mode measures the gap between two clock times: 9:15 to 18:40 is 9 hours 25 minutes. A shift that ends after midnight is handled automatically.
The second mode adds and subtracts durations — three blocks of work in a day, or the time left after part of a budget has been spent.
Common intervals
Duration
9 h 25 min
In decimal hours: 9.42 · Total minutes: 565 · Total seconds: 33,900
How to count hours and minutes
- Convert both moments to minutes past midnight: 9:15 is 555, 18:40 is 1,120.
- Subtract: 1,120 − 555 = 565 minutes.
- Divide by 60 with a remainder: 565 = 9 × 60 + 25, so 9 hours 25 minutes.
- If the end is smaller than the start, add a day — 1,440 minutes.
Decimal hours versus hours and minutes
Timesheets and invoices use decimal hours: 9 hours 25 minutes is 9.42 hours, not 9.25. The mistake appears whenever minutes are copied straight after the decimal point.
The conversion is simple: divide minutes by 60. A quarter hour is 0.25, a third is 0.33, three quarters is 0.75. Going back, 0.4 hours is 24 minutes.
Minutes in decimal hours
| Minutes | Decimal hours |
|---|---|
| 5 | 0.083 |
| 10 | 0.167 |
| 15 | 0.25 |
| 20 | 0.333 |
| 30 | 0.5 |
| 40 | 0.667 |
| 45 | 0.75 |
| 50 | 0.833 |
Crossing midnight
A shift from 22:00 to 06:00 lasts 8 hours even though the end time looks smaller than the start. The calculator adds a day and says so on a separate line, so the result does not read like a bug.
For anything longer than 24 hours, count with dates instead — the days between dates calculator covers the full span.
Hours between two times: examples
| Start | End | Duration |
|---|---|---|
| 22:00 | 06:00 | 8 hours |
| 09:00 | 18:00 | 9 hours |
| 08:30 | 17:15 | 8 hours 45 minutes |
| 23:30 | 01:00 | 1 hour 30 minutes |
Frequently asked questions
How do I calculate the time between two moments?
Convert both to minutes past midnight, subtract the start from the end and divide the remainder by 60. The calculator does it in one step.
How do I convert minutes to decimal hours?
Divide the minutes by 60. 25 minutes is 0.42 hours and 45 minutes is 0.75 hours.
How do I count a shift that ends after midnight?
Enter the times as they are: the calculator adds a day and flags it. From 22:00 to 06:00 the answer is 8 hours.
Can I add several intervals together?
Yes — switch to the second mode and add durations in pairs, carrying the running total into the first field.
Why is the result sometimes negative?
In subtraction mode the second duration can be longer than the first. The minus sign shows a shortfall, not an error.
Updated: 2026-08-09