Hours worked = end time − start time − unpaid breaks. Do it in 24-hour time, take out only breaks that are really unpaid, then divide the leftover minutes by 60 for decimal hours. A day from 8:40 a.m. to 5:15 p.m. with a 30-minute unpaid lunch is 8 h 05 m, or 8.08 hours. Or skip the arithmetic with the time card calculator.
Step 1: Write down the start and end times
Record when work actually started and ended each day, as it happens if you can. A shift split by lunch has four punches: in, out for lunch, back from lunch, and out. If your employer's clock or app shows different times from your own record, keep both; minor differences happen, but the federal rule says major discrepancies "should be discouraged" because they cast doubt on the accuracy of the record (29 CFR 785.48).
Step 2: Convert to 24-hour time
Subtraction is easier in 24-hour ("military") time. Morning times stay the same. For afternoon times add 12 to the hour: 1:15 p.m. is 13:15 and 5:45 p.m. is 17:45. Noon is 12:00 and midnight is 00:00. The military time converter does this for you.
Step 3: Subtract the start from the end
Subtract hours from hours and minutes from minutes. If the end minutes are smaller than the start minutes, borrow 60 minutes from the hours.
Example: 8:40 a.m. to 5:15 p.m. is 17:15 − 8:40. Borrow an hour: 17:15 becomes 16:75, so 16 − 8 = 8 hours and 75 − 40 = 35 minutes. That is 8 h 35 m.
Shifts past midnight: if the shift ends after midnight, add 24 to the end hour. 10:30 p.m. to 7:00 a.m. is 31:00 − 22:30 = 8 h 30 m. The time duration calculator handles start and end dates as well as times.
Step 4: Take out unpaid breaks, and only those
Whether to subtract a break depends on the break. Rest periods of short duration, running from 5 minutes to about 20 minutes, are customarily paid as working time and "must be counted as hours worked" (29 CFR 785.18). A bona fide meal period is not work time, but only if the employee is "completely relieved from duty for the purposes of eating regular meals," and the same rule says ordinarily 30 minutes or more is long enough (29 CFR 785.19). An employee who must eat at their desk or stay at their machine is working while eating.
8 h 35 m minus a 30-minute unpaid lunch = 8 h 05 m.
See Are breaks paid? for the federal rule and the state rules.
Step 5: Convert to decimal hours
Payroll usually wants decimal hours. Divide the minutes by 60 and add them to the hours: 5 ÷ 60 = 0.08, so 8 h 05 m is 8.08 hours. Never write 8.05, which would be 3 minutes. Every 6 minutes is 0.1 of an hour. The minutes to decimal chart lists every minute.
Step 6: Total the week, then check overtime
Add the day totals for the workweek. For most hourly employees in the U.S., hours over 40 in the workweek are overtime, paid at one and a half times the regular rate. The workweek is a fixed, recurring period of 168 hours (seven 24-hour periods). It can start on any day and at any hour, and hours are not averaged across two or more weeks (U.S. Department of Labor, Overtime Pay). So in a two-week pay period, work out each week separately. California adds daily overtime; see federal and California overtime.
A complete example
| Day | In | Out | Break | Hours | Decimal |
|---|---|---|---|---|---|
| Mon | 7:55 | 4:30 | 30 min | 8:05 | 8.08 |
| Tue | 8:00 | 5:10 | 30 min | 8:40 | 8.67 |
| Wed | 8:05 | 4:35 | 30 min | 8:00 | 8.00 |
| Thu | 7:50 | 6:20 | 45 min | 9:45 | 9.75 |
| Fri | 8:00 | 3:00 | 30 min | 6:30 | 6.50 |
| Week total | 41:00 | 41.00 | |||
Times are a.m. for the morning punch and p.m. for the afternoon one. The week is 40 regular hours and 1 overtime hour. At $19.00 an hour that is $760.00 + $28.50 = $788.50 before tax. You can reproduce it in seconds with the time card calculator.
Add minutes first, then convert once. Rounding each day to two decimals before adding can drift. Five days of 8 h 05 m are exactly 40 h 25 m, which is 40.42 hours, but five days of 8.08 add to 40.40. The law does not tell you to do it this way; it is simply the way to keep the arithmetic exact.
What counts as hours worked
The federal fact sheet on hours worked (DOL Fact Sheet #22, Hours Worked Under the FLSA) sets out the main principles:
- Work you were not asked to do. Work "suffered or permitted" is work time. An employee who keeps working after the shift to finish a task or correct errors is working, and the reason is immaterial (29 CFR 785.11).
- Waiting. Whether waiting is work depends on the facts: an employee "engaged to wait" (a secretary reading a book while waiting for dictation) is working, while one who is "waiting to be engaged" is not.
- On call. An employee required to remain on call on the employer's premises is working. One on call at home, or free to leave a message where they can be reached, is generally not, though more constraints on freedom can change that.
- Travel. Ordinary travel from home to work is not work time. Travel from job site to job site during the workday is.
- Coming early or staying late without working. Where time clocks are used, an employee who voluntarily clocks in early or stays late but does no work need not be paid for that time (29 CFR 785.48).
Special cases, such as sleeping time on long shifts and training, have their own rules in the fact sheet.
Common mistakes
- Entering minutes as decimals. 8:40 is 8.67 hours, not 8.40.
- Subtracting paid breaks. Short rest breaks are hours worked.
- Averaging overtime over a two-week pay period. Overtime is measured per workweek.
- Leaving out unrecorded work. Work the employer knows about is work time even if nobody asked for it.
- Uneven rounding. See time clock rounding and the 7-minute rule.
Sources and limits
The rules above come from the DOL Fact Sheet #22, Hours Worked Under the FLSA and the U.S. Department of Labor, Overtime Pay pages, and from the regulations 29 CFR 785.11, 29 CFR 785.18, 29 CFR 785.19 and 29 CFR 785.48, which we read on September 26, 2026. The Department of Labor's site does not allow automated readers, so we read its pages through copies from the Internet Archive taken in 2026; the regulations we read on the government's eCFR site. The fact sheet is dated July 2008, and rules change. Employers and union contracts can pay more than the law requires, and state law may add to it. This is general information, not legal or payroll advice. If you think you have been underpaid, contact the U.S. Department of Labor's Wage and Hour Division or your state labor department.