How to Calculate Work Hours

Use start time, end time, and break duration to calculate total hours worked.

Step-by-Step

Calculating work hours is easiest when you handle the shift in a consistent order. First find the full time between clock-in and clock-out. Then subtract unpaid breaks. Finally, convert the remaining hours and minutes into the format required by your timesheet, invoice, or payroll system.

  1. Write down your start time.
  2. Write down your end time.
  3. Subtract start time from end time.
  4. Subtract unpaid breaks.
  5. Convert minutes to decimal hours if needed.

Why Breaks Matter

Breaks are one of the most common reasons a work-hours total looks wrong. Paid rest breaks are usually included in paid time, while unpaid meal breaks are usually deducted. If you enter a 30-minute unpaid lunch, an 8-hour span from 9:00 AM to 5:00 PM becomes 7 hours 30 minutes of net paid time.

When you are not sure whether a break is paid or unpaid, keep the break visible in your notes and confirm the rule with your employer or payroll provider. This is especially important for long shifts, country-specific rules, union agreements, and schedules where breaks are automatically deducted.

Example

Start at 9:00 AM, end at 5:00 PM, with a 30-minute break.

8 hours - 30 minutes = 7 hours 30 minutes = 7.5 hours

Overnight Shift Example

If a shift starts at 10:00 PM and ends at 6:00 AM, it crosses midnight. Count 10:00 PM to midnight as 2 hours, then midnight to 6:00 AM as 6 hours. The total duration is 8 hours before breaks. If the unpaid break is 30 minutes, the net result is 7.5 hours.

Decimal Hours for Payroll

Payroll systems often use decimal hours instead of hours and minutes. To convert minutes, divide by 60. Fifteen minutes is 0.25 hours, 30 minutes is 0.5 hours, and 45 minutes is 0.75 hours. Do not enter 7 hours 30 minutes as 7.30, because 7.30 means 7.3 decimal hours, not 7.5 hours.

Common Mistakes

  • Mixing up AM and PM when entering shift times.
  • Forgetting to subtract unpaid meal breaks.
  • Adding weekly totals before checking each daily shift.
  • Using decimal minutes incorrectly, such as 7.45 instead of 7.75.

For instant results, use the Timesheet Calculator or Time Duration Calculator.

These calculations are for planning and checking. For official payroll or employment decisions, confirm the final total with the system or person responsible for your timesheet.