How to calculate hours worked
By Dexaloop · Updated 27 October 2026 · Checked against the sources listed below
To calculate hours worked, take each shift's clock-out time minus its clock-in time, subtract any unpaid meal break, then add the days together for the week. Short rest breaks stay in, a shift past midnight needs 24 hours added to the end time, and minutes must be divided by 60 before you multiply by an hourly rate. This guide walks through each step with examples. The break rules quoted are US federal rules from the Department of Labor (DOL), checked on 27 October 2026; states and employers can add more.
Step 1: find the length of each shift
Write every time in the same format first. The 24-hour clock avoids most mistakes: 1:30 PM is 13:30 and 9:15 PM is 21:15.
Then subtract start from finish. Work in hours and minutes, borrowing 60 minutes when you need to, just as you would borrow 10 in ordinary subtraction.
Example: in at 08:45, out at 17:15. From 08:45 to 16:45 is 8 hours, and 16:45 to 17:15 is 30 minutes, so the shift is 8 hours 30 minutes.
Step 2: take off unpaid breaks, and only those
US federal law does not make employers give breaks. The DOL says: "Federal law does not require lunch or coffee breaks." But when breaks are given, the rules on which ones are paid are clear:
| Type of break | Typical length (DOL) | Counts as hours worked? |
|---|---|---|
| Rest or coffee break | About 5 to 20 minutes | Yes, it is paid work time |
| Bona fide meal period | Usually 30 minutes or more | No, if you are fully relieved from duty |
| Meal "break" spent working | Any length | Yes |
The key test for a meal period is in DOL Fact Sheet 22: "The employee must be completely relieved from duty for the purpose of eating regular meals." The DOL gives the example of an office worker who eats at their desk while answering the phone. That person is working, so the time is paid.
Back to the example: an 8 hour 30 minute shift with a 30-minute unpaid lunch is 8 hours worked. If the same person also took two 10-minute coffee breaks, those stay in. The total is still 8 hours.
Some states require meal or rest breaks and set their own pay rules. Check your state labor department if you work outside the federal minimum.
Step 3: shifts that cross midnight
A night shift breaks the simple sum, because the clock-out time is smaller than the clock-in time. There are two easy fixes:
- Add 24 hours to the clock-out time. In at 22:00, out at 06:30. Treat 06:30 as 30:30, then subtract: 30:30 minus 22:00 is 8 hours 30 minutes.
- Split at midnight. 22:00 to 24:00 is 2 hours, and 00:00 to 06:30 is 6 hours 30 minutes. Together that is 8 hours 30 minutes.
Take off a 30-minute unpaid meal and the night shift is 8 hours worked. A result that comes out negative, or impossibly long such as 15 hours 30 minutes for this shift, is the sign that midnight was not handled.
Step 4: turn hours and minutes into decimal hours
Payroll multiplies hours by a rate, so 7 hours 40 minutes has to become a single number. Divide the minutes by 60 and add the result to the hours.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 5 | 0.08 | 35 | 0.58 |
| 10 | 0.17 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 30 | 0.50 | 55 | 0.92 |
The most common error on a time card is writing 7 hours 40 minutes as 7.40. It is 7.67. At $15 an hour, 7.67 hours pays $115.00 (7 2/3 × $15), while 7.40 pays only $111.00. Over a year of such days the gap adds up.
Worked example: one full week
Sam is paid $15 an hour, takes a 30-minute unpaid lunch each day, and works a night shift on Friday.
| Day | In | Out | Shift | Unpaid meal | Worked |
|---|---|---|---|---|---|
| Monday | 08:45 | 17:15 | 8:30 | 0:30 | 8:00 |
| Tuesday | 08:50 | 17:30 | 8:40 | 0:30 | 8:10 |
| Wednesday | 09:00 | 18:10 | 9:10 | 0:30 | 8:40 |
| Thursday | 08:45 | 16:00 | 7:15 | 0:30 | 6:45 |
| Friday | 22:00 | 06:30 | 8:30 | 0:30 | 8:00 |
Add the hours and the minutes separately: 38 hours and 95 minutes. 95 minutes is 1 hour 35 minutes, so the week is 39 hours 35 minutes. As a decimal that is 39 + 35 ÷ 60 = 39.58 hours, and the pay is 39 7/12 × $15 = $593.75.
The week is under 40 hours, so no federal overtime is due. Had it gone over, the DOL rule is that hours over 40 in a workweek are paid at not less than time and one-half the regular rate.
Time that counts even when it feels like waiting
Hours worked are not only the minutes spent on a task. DOL Fact Sheet 22 says the workday generally runs from the start of your first principal activity to the end of your last one, so it can be longer than the scheduled shift. It also separates two kinds of waiting:
- Engaged to wait. If you are on the job and waiting is part of it, such as a worker standing by for the next delivery, that time is work and is paid.
- Waiting to be engaged. If you are fully free to leave and use the time for yourself, it is generally not work time.
On a time card this mostly shows up as clock-in and clock-out times that should not be trimmed back to the "real" work. If you were required to be there and ready, the time belongs on the card.
Rounding clock times
Some employers round punches. The federal rule in 29 CFR 785.48 allows start and stop times to be recorded to the nearest 5 minutes, tenth of an hour or quarter of an hour, but only if, over time, employees are still paid for all the time they actually worked. A rule that always rounds down does not meet that test. The same section notes that "major discrepancies should be discouraged" between clock records and real hours.
Common mistakes
- Subtracting short breaks. Coffee breaks of up to about 20 minutes are paid time under federal rules.
- Reading minutes as decimals. 8:45 means 8.75 hours, not 8.45.
- Forgetting midnight. Always check that night shifts come out at a sensible length.
- Adding minutes past 60. Carry each 60 minutes into the hours column before converting.
- Taking off a meal break that was worked through. If you were not fully relieved from duty, the time counts.
For a full week of punches, the calculator below does the subtraction, the midnight handling and the decimal conversion at once.
Add up a time card: tools.dexaloop.com/time-card-calculator/. Free, no sign-up, and it runs on your device.
Questions
Do I subtract a 15 minute break from my hours?
Not under US federal rules. The Department of Labor treats short rest breaks, usually 5 to 20 minutes, as paid work time. Only a real meal break, usually 30 minutes or more, where you are fully relieved from duty, can be left unpaid.
How do I convert minutes to decimal hours?
Divide the minutes by 60. 30 minutes is 0.5, 45 minutes is 0.75, and 40 minutes is about 0.67. So 7 hours 40 minutes is 7.67 hours, not 7.40.
How do I count a shift that goes past midnight?
Add 24 hours to the clock-out time before you subtract, or count the hours to midnight and the hours after it, then add them. A shift from 10:00 PM to 6:30 AM is 8.5 hours before any unpaid meal break.
Is my lunch break paid if I answer the phone during it?
Under federal rules it should be. The Department of Labor says an employee eating at their desk while answering the phone has not been completely relieved from duty, so the time is work time.
Can my employer round my clock times?
Federal rules allow rounding to the nearest 5 minutes, tenth of an hour or quarter hour, as long as over time it does not leave employees underpaid for the time they actually worked.
Sources
- US Department of Labor: Breaks and meal periods
- US Department of Labor: Fact Sheet 22, Hours worked under the FLSA
- 29 CFR 785.48, Use of time clocks (Legal Information Institute, Cornell Law School)
- US Department of Labor: Overtime pay
This guide is general information, not legal, tax or financial advice. Rules change; check the official source for your own case. Found a mistake? Email support@dexaloop.com.