How to calculate hours worked, including lunch

The method in three steps

Every hours-worked sum is the same three steps. Do them in this order, so a lunch break or a time after noon doesn’t trip you up.

1. Write both times in 24-hour form. Add 12 to any time from 1:00 PM to 11:59 PM, so 5:15 PM becomes 17:15. Noon stays 12:00, and 12:20 AM (just after midnight) becomes 0:20.
2. Subtract the start from the end. If the end minutes are smaller than the start minutes, borrow one hour as 60 minutes. 17:15 minus 8:45 becomes 16:75 minus 8:45, which is 8:30.
3. Take off unpaid breaks. Subtract the break in minutes. Convert to a decimal only at the very end, by dividing the leftover minutes by 60.

Example: a shift with a fixed 30-minute lunch

You start at 8:45 AM, finish at 5:15 PM and take an unpaid 30-minute lunch that isn’t punched on a clock.

17:15 − 8:45 = 8 h 30 min on site

8 h 30 min − 30 min lunch = 8 h 00 min = 8.00 hours worked

With a 45-minute lunch the same shift is 7 h 45 min, which is 7.75 hours, not 7.45. The decimal part is a fraction of an hour, so 45 minutes is 45 ÷ 60 = 0.75.

Example: when you clock out for lunch

With four punches (in, out for lunch, back from lunch, out), work out the two working blocks and add them. Don’t subtract a standard 30 minutes, because the real break is rarely exactly that.

Lunch here ran from 12:03 to 12:41, which is 38 minutes. Taking a flat 30 minutes off the 8 h 38 min between the first and last punch would give 8 h 08 min and overstate the day by 8 minutes. The time card with lunch takes all four punches and does this for each day.

Shifts that cross midnight

If the end time is earlier than the start time, the shift ran past midnight. Add 24 hours to the end time before you subtract.

10:00 PM to 6:30 AM: 6:30 + 24:00 = 30:30, and 30:30 − 22:00 = 8 h 30 min

8 h 30 min − 30 min unpaid break = 8 h 00 min

Payroll usually counts an overnight shift on the day it started, but some employers split it at midnight. That matters when a shift straddles the end of a workweek, so check how your employer records it.

Which breaks come off your hours

Only unpaid breaks are subtracted. In the United States, the Department of Labor’s guidance on the Fair Labor Standards Act (FLSA) draws the line like this:

• Short rest breaks, usually 20 minutes or less, count as hours worked. Don’t subtract them.
• Real meal periods, typically 30 minutes or more, usually don’t need to be paid, but only if you are completely relieved from duty.
• Eating at your desk while answering phones is not a meal break. That time counts as work.

Many states have their own break and meal rules, and employers can pay for breaks the law doesn’t require them to pay for. This guide explains the arithmetic. It isn’t legal advice, so check your state’s labor department or your employer’s policy if your pay depends on the answer.

Adding up a week

Total each day in hours and minutes, add the minutes for the whole week, and convert to a decimal once. Here is a typical week:

The days add up to 2,360 minutes, and 2,360 ÷ 60 = 39.33 hours. If you round each day to two decimals first (8.00 + 8.17 + 7.17 + 9.25 + 6.75) you get 39.34 instead, because the rounding errors pile up. The time card calculator adds the minutes for you, and the decimal hours calculator converts a total like 39:20 in one step.

Common mistakes

• Reading decimals as minutes. 7.45 hours is 7 hours 27 minutes (0.45 × 60 = 27), not 7 hours 45 minutes.
• Forgetting the afternoon switch. 1:00 PM minus 9:00 AM is 4 hours, not minus 8. Write 13:00 first.
• Subtracting a standard lunch when the punches show a longer or shorter one.
• Rounding every day before adding the week.
• Subtracting paid rest breaks, which shortens the day you are paid for.

Sources

• U.S. Department of Labor, Fact Sheet #22: Hours Worked Under the FLSA. Rest periods and meal periods