How to Calculate Hours Worked

Quick answer: the hours worked formula

The basic calculation is:

Hours worked = clock-out time − clock-in time − unpaid breaks

For example, a shift from 8:30 AM to 5:15 PM lasts 8 hours 45 minutes. Subtract a 30-minute unpaid lunch and the net worked time is 8 hours 15 minutes, or 8.25 decimal hours.

If you only need the answer, use the Work Hours Calculator. The rest of this guide explains how the calculation works, including lunch breaks, overnight shifts, split shifts, weekly totals and decimal conversion.

Step 1: find the elapsed time between clock-in and clock-out

Start with the full span of the shift before breaks. If you clock in at 9:00 AM and clock out at 5:30 PM, the elapsed shift is 8 hours 30 minutes.

This is gross elapsed time, not necessarily paid or net worked time. The next step is to account for breaks that should be excluded from the timesheet.

Step 2: subtract unpaid lunch or break time

Subtract only break time that should be treated as unpaid for the record you are preparing. If a break is paid, or if your timekeeping system has already removed it, do not subtract it a second time.

Example: a 9:00 AM to 5:30 PM shift is 8 hours 30 minutes. With a 30-minute unpaid lunch:

8h 30m − 30m = 8h 00m worked

With a 45-minute unpaid lunch:

8h 30m − 45m = 7h 45m worked

For a full weekly time card with daily lunch deductions, use the Timesheet Calculator With Lunch Break.

Step 3: handle overnight shifts correctly

An overnight shift has a clock-out time that looks earlier than the clock-in time because it ends on the next calendar day. Do not subtract the times as if they happened on the same date.

Example: clock in at 10:00 PM and clock out at 6:00 AM. The elapsed shift is 8 hours. If there is a 30-minute unpaid break:

8h 00m − 30m = 7h 30m worked

A reliable way to think about the math is to add 24 hours to the end time whenever clock-out is earlier than clock-in. Our work-hours and timesheet calculators handle that rollover automatically.

Step 4: add split shifts separately

Some workdays have two or more work periods. Instead of treating the full day as one continuous shift, calculate each work period and add them together.

Example:

This avoids accidentally counting the one-hour gap between shifts as worked time. The Weekly Timesheet Calculator supports two work periods per day.

How to calculate weekly hours worked

Calculate each day after subtracting that day's unpaid breaks, then add the daily net totals. Do not subtract the same breaks again from the weekly total.

If you need to separate regular and overtime hours, calculate the worked-time total first. Overtime treatment is a separate step. Our Overtime Calculator lets you choose the threshold and multiplier rather than assuming one rule applies to every worker.

How to convert worked time to decimal hours

Timesheets, payroll systems and invoices often use decimal hours. The digits after the decimal point are fractions of an hour, not clock minutes.

Decimal hours = whole hours + (minutes ÷ 60)

A common mistake is writing 8 hours 30 minutes as 8.30. That is incorrect: 0.30 of an hour is 18 minutes. For exact conversions, use the Decimal Hours Calculator or Hours & Minutes Calculator. For a full lookup table and spreadsheet formulas, see the Minutes to Decimal Hours Conversion Chart.

Worked hours, paid hours and payroll hours are related but not identical

Worked hours usually describe the time remaining after excluded breaks are removed. Paid hours can depend on how a specific employer treats breaks, leave, minimum guarantees or other paid time. Payroll hours often describe the numeric format sent into payroll, frequently as decimal hours.

For that reason, do the time arithmetic first and keep policy decisions separate. If you already know the daily hours and minutes and simply need a payroll-ready weekly total, use the Payroll Hours Calculator.

Common mistakes when calculating work hours

1. Treating clock minutes as decimal fractions

8:30 is 8.50 decimal hours, not 8.30.

2. Subtracting a break twice

If clock-in/clock-out records already exclude a meal period because the worker clocked out and back in, do not also subtract the same break as a separate deduction.

3. Ignoring midnight

10:00 PM to 6:00 AM is an 8-hour elapsed shift, not a negative result.

4. Counting the gap in a split shift

Calculate each work period separately so non-working gaps are not added to the total.

5. Rounding too early

Keep calculations in minutes for as long as possible. Convert or round the final result according to the timekeeping or payroll method you actually need.

6. Mixing time calculation with overtime rules

First determine total hours worked. Then apply the overtime threshold or policy relevant to the situation. Keeping those steps separate makes the calculation easier to audit.

Manual calculation vs a work hours calculator

Manual calculation is useful when checking one shift or auditing a result. A calculator becomes more useful when you have several days, overnight work, different break lengths, decimal conversions or a weekly total.

For one repeated schedule, use the Work Hours Calculator. For daily clock-in and clock-out entries, use the Weekly Timesheet Calculator. For a weekly time card that specifically deducts lunch breaks, use the Timesheet Calculator With Lunch Break.