Why time math goes wrong
An hour has 60 minutes, not 100, so ordinary subtraction gives the wrong answer. From 9:40 to 11:20 is not 11.20 − 9.40 = 1.80. You borrow an hour first: 80 − 40 = 40 minutes and 10 − 9 = 1 hour, so the answer is 1 hour 40 minutes. This calculator turns every time into seconds, does the arithmetic, and converts back, so the borrowing is never missed.
Minutes to decimal hours
Most timesheets and payroll systems want hours as a decimal: 7 hours 45 minutes is entered as 7.75. Divide the minutes by 60 to get the decimal part.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 6 | 0.10 | 36 | 0.60 |
| 12 | 0.20 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 48 | 0.80 |
| 30 | 0.50 | 50 | 0.83 |
The other way round, multiply the decimal part by 60: 1.5 hours is 1 hour 30 minutes, and 2.2 hours is 2 hours 12 minutes.
Hours worked and breaks
Enter clock-in and clock-out times with the unpaid break to get the hours worked. In the United States, federal law does not require meal or rest breaks, but short breaks that are given are usually counted as paid time, while a bona fide meal period of 30 minutes or more is usually unpaid. Several states have their own break rules, so check your state labor office for the exact requirement.
Source: U.S. Department of Labor, Breaks and Meal Periods; 29 CFR 785.18–785.19
FAQ
Is 12:00 PM noon or midnight?
12:00 PM is noon and 12:00 AM is midnight. Results show both the 12-hour and the 24-hour time so there is no doubt.
How do I calculate a night shift?
Just enter the times. If the end is earlier than the start, the calculator assumes the shift crosses midnight. For periods longer than a day, use the Date Calculator.
Can I total video lengths or study time?
Yes. Put each length on its own line in the "Add up durations" tab, for example 12:45 or 1:02:30. Formats can be mixed.
Related tools
- Date Calculator — days between dates
- Percentage Calculator — percent change