How to Calculate Work Hours: Breaks, Overnight Shifts & Weekly Totals
Updated October 6, 2026
To calculate work hours for a standard shift, find the elapsed time between clock-in and clock-out, subtract only unpaid breaks, and convert the remaining minutes into decimal hours if needed. 8:30 AM to 4:45 PM with a 30-minute unpaid lunch equals 7 hours 45 minutes, or 7.75 hours.
This guide shows how to calculate one shift, overnight hours, split shifts, and weekly totals. It also explains how to check a simple overtime estimate without confusing daily hours with a whole workweek.
Calculate Work Hours Automatically
Check one shift, deduct unpaid breaks, and estimate pay using the settings you enter. For several days, use the Timesheet Calculator.
Use the Work Hours CalculatorWho This Guide Is For
- Hourly employees tracking shifts
- Freelancers calculating billable hours
- Managers reviewing employee timesheets
- Payroll staff calculating worked time
- Remote workers tracking schedules
- Contractors estimating weekly earnings
What Are Work Hours?
For a standard shift, work hours include the elapsed shift time after properly unpaid breaks are removed. Paid rest breaks stay in the total. Other compensable activities may also need to be counted under the rules that apply to your job.
Record your actual start and finish times, including dates for overnight shifts. Use the same unit for every part of the calculation: minutes are often easiest.
This basic formula works for:
- Daily work shifts
- Weekly timesheets
- Payroll calculations
- Finding worked time before applying overtime rules
- Freelance billable hours
How to Calculate Work Hours Step by Step
1. Record Your Start Time
Write down the exact time you started working.
Example: 8:30 AM
2. Record Your End Time
Write down the time your shift ended.
Example: 4:45 PM
3. Calculate Total Time Between Hours
Convert the times to a 24-hour clock, then minutes after midnight: 8:30 AM is (8 × 60) + 30 = 510 minutes. 4:45 PM is 16:45, or (16 × 60) + 45 = 1,005 minutes. Subtract: 1,005 − 510 = 495 minutes.
From 8:30 AM to 4:45 PM equals:
8 hours and 15 minutes
4. Subtract Unpaid Breaks
If you took a 30-minute unpaid lunch break:
8 hours 15 minutes − 30 minutes = 7 hours 45 minutes worked
5. Convert Minutes Into Decimal Hours
Many payroll systems use decimal hours instead of standard hours and minutes.
To convert minutes into decimal hours:
Total Worked Minutes ÷ 60 = Decimal Work Hours
In the example above, 495 − 30 = 465 worked minutes. Divide by 60: 465 ÷ 60 = 7.75 hours. For a quick check, enter your shift and unpaid breaks in the Break Time Calculator.
Which Breaks Should You Subtract?
Deduct only properly unpaid breaks. A calculator cannot determine whether a break legally qualifies as unpaid. For covered U.S. employees, the Department of Labor explains that short rest breaks, generally 20 minutes or less, count as hours worked. A bona fide meal period generally requires being completely relieved of duties. Answering work calls while eating can mean the time still counts. Read the Department of Labor guidance on hours worked. Additional state requirements and rules outside the U.S. may differ.
Multiple breaks: An 8-hour shift with a 30-minute unpaid lunch and two paid 10-minute breaks has 7.50 work hours. Deduct only the lunch. If two genuine unpaid breaks total 45 minutes, the same shift has 7.25 work hours.
Minutes to Decimal Hours Conversion Chart
| Minutes | Decimal Hours |
|---|---|
| 5 | 0.08 |
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 45 | 0.75 |
| 50 | 0.83 |
These values are rounded to two decimal places. 7 hours 45 minutes is 7.75 hours, not 7.45. Divide the minute portion by 60, then add the whole hours.
Keep the original minutes when adding several entries and round the final display. Six 10-minute periods total 1 hour; adding six rounded 0.17 values would incorrectly give 1.02 hours. See our minutes to decimal hours guide for more examples.
Example of Calculating Daily Work Hours
- Start time: 9:00 AM
- End time: 5:30 PM
- Lunch break: 1 hour unpaid
Total time between 9:00 AM and 5:30 PM: 8 hours 30 minutes
After subtracting the lunch break: 7 hours 30 minutes worked
Decimal format: 7.5 hours
How to Calculate Weekly Work Hours
To calculate weekly work hours, add each day’s worked time after unpaid deductions. Add minutes first, then divide by 60, or carry every 60 minutes into an hour. Use the Timesheet Calculator for several days.
Tuesday: 7.5 hours
Wednesday: 8 hours
Thursday: 8.5 hours
Friday: 7 hours
Total Weekly Hours = 39 Hours
The single-shift Work Hours Calculator does not include the other days of a workweek. Setting its threshold to 40 hours does not make it a weekly calculation. Add all relevant days before applying a weekly overtime threshold.
You can estimate overtime earnings using our Overtime Pay Calculator.
How to Calculate Overtime Hours and Estimated Pay
Identify the applicable rule first. For covered, nonexempt U.S. employees, the usual federal rule is overtime after 40 hours worked in a workweek at at least 1.5 times the regular rate. Some jurisdictions have additional daily requirements; exemptions and special rules can apply. The Department of Labor guidance linked above provides the federal context.
A Simple Weekly Overtime Example
Assume 43 hours worked, a 40-hour weekly threshold, a $20 regular hourly rate, and a 1.5 overtime multiplier:
- Regular hours: 40.
- Overtime hours: 43 − 40 = 3.
- Regular pay: 40 × $20 = $800.
- Overtime pay: 3 × ($20 × 1.5) = $90.
- Estimated gross pay: $890.
This assumes a simple hourly rate with no adjustments. Bonuses, different pay rates, taxes, deductions, and other payroll factors can change the result.
How to Calculate Overnight Shift Hours
Overnight shifts pass midnight, which can make calculations more confusing manually.
- Start: 10:00 PM
- End: 6:00 AM
- Break: 30 minutes unpaid
10:00 PM → Midnight = 2 hours
Midnight → 6:00 AM = 6 hours
Total = 8 hours
Minus break = 7.5 hours worked
If you regularly work overnight shifts, a Time Duration Calculator can simplify time tracking significantly.
This example assumes the end is on the next day and the shift is shorter than 24 hours. For a shift lasting 24 hours or longer, record the dates as well as the times. If clocks change or you cross time zones, use dated timestamps with UTC offsets to calculate actual elapsed time; a clock-time-only calculation may differ.
How to Calculate Split Shifts
Add each separate work period: 8:00 AM–12:00 PM is 4 hours, and 2:00 PM–6:30 PM is 4 hours 30 minutes. The total is 8.50 hours. The two-hour gap is already excluded, so do not deduct it again. Subtract only additional unpaid breaks within those work periods. Whether a gap is paid depends on the circumstances and applicable rules.
Common Work Hour Calculation Mistakes
- Forgetting to subtract unpaid breaks
- Mixing up AM and PM times
- Incorrect decimal conversions
- Calculation errors with overnight shifts
- Adding weekly totals incorrectly
- Applying a weekly overtime threshold to just one day
- Deducting lunch twice when it is already excluded between clocked work periods
- Rounding minute conversions before adding weekly totals
Why Accurate Work Hour Tracking Matters
Accurate work hour calculations help:
- Ensure correct employee pay
- Reduce payroll disputes
- Improve timesheet accuracy
- Track productivity more effectively
- Estimate overtime earnings correctly
- Improve freelance invoicing accuracy
Frequently Asked Questions
How do I calculate work hours manually?
Find elapsed time between your actual start and end dates and times, subtract unpaid break minutes once, then divide worked minutes by 60 for decimal hours.
How many hours is 9 AM to 5 PM with a 30-minute lunch?
The shift spans 8 hours. With a 30-minute unpaid lunch, work time is 7 hours 30 minutes, or 7.50 hours. If lunch is paid, do not deduct it.
How do I convert hours and minutes into decimal hours?
Divide the minute portion by 60, then add the whole hours. For example, 7 hours 45 minutes equals 7 + (45 ÷ 60), or 7.75 hours.
How do I calculate overnight shift hours?
For a shift shorter than 24 hours, add the time before midnight to the time after midnight, then subtract unpaid breaks. A 10 PM–6 AM next-day shift with a 30-minute unpaid break is 7.50 hours, assuming no clock change.
How do I calculate weekly work hours?
Add daily worked minutes after unpaid deductions, then divide the weekly minutes by 60. Use the Timesheet Calculator for several days.
Does every shift over 8 hours qualify for overtime?
No. Eligibility and thresholds depend on the applicable rules. Some rules use daily thresholds and others use weekly totals. Check the rule that applies before estimating overtime.
Calculate Hours Worked Instantly
Use the Work Hours Calculator for one shift and an estimated pay breakdown. Use the Timesheet Calculator for a full week.
Open Work Hours Calculator