How to Calculate Hours Worked With Lunch Breaks

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The Formula for Hours Worked

The formula is:

Net hours = Clock-out time − Clock-in time − Unpaid break time

Only unpaid break durations are subtracted in these examples. Paid breaks remain part of hours worked.

Work in hours and minutes first, then convert to decimal hours if needed for payroll or a spreadsheet:

Decimal hours = Hours + Minutes ÷ 60

Useful conversions:

• 15 minutes = 0.25 hours
• 30 minutes = 0.50 hours
• 45 minutes = 0.75 hours
• 60 minutes = 1.00 hour

Keep the two formats separate in your notes. 7:30 means 7 hours and 30 minutes. 7.50 means 7 and one-half hours in decimal form. Do not write 7.30 when you mean 7 hours 30 minutes.

Same-Day Example: 09:00 to 17:00 With a 30-Minute Break

Take a standard daytime shift:

1. Find gross time: 17:00 − 09:00 = 8 hours
2. Subtract the unpaid lunch: 8 hours − 30 minutes
3. Net time: 7 hours 30 minutes
4. Decimal form: 7 + 30 ÷ 60 = 7.50 hours

So 09:00–17:00 with a 30-minute unpaid break is 7:30 or 7.50 hours.

Another common pattern is 08:00–17:00 with a 60-minute unpaid break:

1. Gross time: 17:00 − 08:00 = 9 hours
2. Subtract unpaid lunch: 9 hours − 1 hour
3. Net time: 8:00

The important check is whether AM and PM are correct and whether the break was unpaid and duty-free. A 30-minute period labeled “lunch” is not automatically unpaid; its treatment depends on the actual circumstances, not the label alone.

Multiple Paid and Unpaid Breaks

Many shifts include more than one break. Add all unpaid, duty-free break time together and subtract that total. Do not subtract paid rest breaks.

For example, consider 08:00–16:30 with:

• 30-minute unpaid lunch
• Two 15-minute paid rest breaks

Calculation:

1. Gross time: 16:30 − 08:00 = 8 hours 30 minutes
2. Unpaid break total: 30 minutes
3. Paid break total: 30 minutes, but not subtracted
4. Net time: 8:30 − 0:30 = 8:00, or 8.00 hours

Under the covered US federal framework, short rest periods of about 5 to 20 minutes must be counted as hours worked. A 15 minute rest within this range must not be deducted merely because it is called duty free. Actual classification depends on applicable law and facts and cannot be established by mechanically subtracting interruption minutes. Other rules outside this covered federal setting can differ. Under 29 CFR 785.19, a bona fide duty-free meal period is not counted as hours worked; such periods are ordinarily 30 minutes or longer, although the particular circumstances can differ. Therefore, check whether the employee was fully relieved of duties, not only what the break was called.

Under the covered US federal framework, a bona fide meal period requires complete relief from duties, so required duties performed during a 30 minute lunch raise a question about whether that standard is met for the period at issue. Such a period interrupted by 10 minutes of required duties must not automatically be treated as 20 unpaid minutes. Actual classification depends on applicable law and facts and cannot be established by mechanically subtracting interruption minutes. Other rules outside this covered federal setting can differ.

Overnight Shifts, Dates, and Daylight Saving

For an overnight shift, include the date change. The formula is the same, but calculate elapsed time across midnight.

Example: clock in 22:00 Monday, clock out 06:00 Tuesday, with a 30-minute unpaid meal break:

1. Monday 22:00 to midnight: 2 hours
2. Midnight to Tuesday 06:00: 6 hours
3. Gross time: 8 hours
4. Less unpaid break: 8 hours − 30 minutes = 7:30, or 7.50 hours

Writing both dates prevents an error such as 06:00 minus 22:00 giving a negative number. In a spreadsheet, use date-plus-time entries, for example 2026-10-05 22:00 to 2026-10-06 06:00.

Daylight-saving transitions need separate care. Clock readings alone can be misleading when clocks move forward or backward. Actual elapsed time controls the arithmetic. If clocks spring forward, a clock interval from 01:30 to 03:30 may represent only one hour of elapsed time. If clocks fall back, a clock interval from 01:00 to 03:00 may represent three hours of elapsed time. Record the date, note that a transition occurred, and calculate from actual start and end instants rather than simply subtracting the displayed clock times.

Weekly Totals and Decimal Mistakes

Calculate each day separately, then add the daily net amounts. Do not average the shifts before subtracting breaks.

Example workweek with five identical shifts:

Thus five 7:30 shifts total 37:30 or 37.50 hours.

Three decimal mistakes cause most weekly errors:

1. Writing minutes as hundredths: 7:30 is 7.50, not 7.30. Likewise, 37:30 is 37.50, not 37.30.
2. Adding decimals and minutes together: Convert everything to either h:min or decimal before adding.
3. Rounding too early: Keep exact minutes for each day and round only the final payroll total, if rounding is permitted and disclosed.

If days differ, add in h:min format by carrying 60 minutes as one hour, or add decimal hours. For example, 8.00 + 7.50 + 7.50 + 6.00 + 8.25 = 37.25 decimal hours, which is 37 hours 15 minutes.

Record-Checking Checklist

Use this checklist before submitting hours or comparing them with a payslip:

• Start and end times show correct AM/PM or 24-hour times.
• Overnight shifts show both start and end dates.
• Each break is marked paid or unpaid based on duty-free status, not only its name.
• Only unpaid break durations were subtracted.
• Gross time, break time, and net time are recorded separately.
• Minutes were converted with Minutes ÷ 60 before using decimals.
• Daily net times were added, not averaged.
• Daylight-saving dates use actual elapsed time, not clock-face subtraction alone.
• Weekly h:min total matches the decimal total; 37:30 should correspond to 37.50.
• Exceptions are noted: missed lunch, interrupted break, early departure, late arrival, or holiday hours.

Keeping the original times and break notes makes corrections much easier than keeping only the final total.

Sources and rule references

• 29 CFR 785.18: short rest periods
• 29 CFR 785.19: meal periods
• 29 CFR 778.104: each workweek stands alone
• 29 CFR 778.105: defining the workweek

Related reading

• Paid Breaks vs Unpaid Lunch: What Counts in Your Work Hours?
• How to Fill Out a Timesheet: A Worked Weekly Example