Quick answer
Hours worked = (end − start) − break. 09:00 to 17:30 with a 30 minute unpaid break is 8:00, or 8 decimal hours.
Enter start and end times and the unpaid break. The calculator returns time worked and decimal hours.
Related tools: Hours Calculator: Hours worked between a start and end time, minus breaks. Time From Now Calculator: Clock time after adding or subtracting minutes. Shift End Time Calculator: End time of a shift of a given length, including an unpaid break.
How to use the Work Hours Calculator
- Type start time (24-hour), for example 09:00.
- Type end time (24-hour), for example 17:30.
- Enter unpaid break (min) (0 or more). It starts at 0.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Start time (24-hour) | Text, such as 09:00 | — |
| End time (24-hour) | Text, such as 17:30 | — |
| Unpaid break | A number, in min | ≥ 0, starts at 0 |
Formula and method
Formula
hours = (end − start) − break
IEEE-754 double precision; shown to the decimals indicated.
Handles shifts that cross midnight.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Start time (24-hour) = 09:00; End time (24-hour) = 17:30; Unpaid break = 30.
| Result | Value |
|---|---|
| Time worked | 8:00 |
| Decimal hours | 8 |
Example 2
Inputs: Start time (24-hour) = 22:00; End time (24-hour) = 06:00; Unpaid break = 45.
| Result | Value |
|---|---|
| Time worked | 7:15 |
| Decimal hours | 7.25 |
The first line is the headline result (time worked). Below it the work Hours Calculator lists decimal hours, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Over a week
Five such days make 40 hours. Multiply decimal hours by the hourly rate for pay.
Where this estimate stops applying
The break cannot exceed the shift. For overnight shifts the end time is the next day.
How the result changes with unpaid break
Holding every other input at the first worked example, this table changes only unpaid break. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Unpaid break | Time worked | Decimal hours |
|---|---|---|
| 15 | 8:15 | 8.25 |
| 30 | 8:00 | 8 |
| 60 | 7:30 | 7.5 |
| 120 | 6:30 | 6.5 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Unpaid break: entering "90" shows "The break is longer than the shift." beside that field and no result.
- Start time (24-hour): left empty shows "Enter start time (24-hour)." beside that field and no result.
Choosing between the Work Hours Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Hours Calculator](/time/hours-calculator/) | start time and end time | Hours worked |
| [Time From Now Calculator](/time/minutes-from/) | start time and minutes to add | Resulting time |
| [Shift End Time Calculator](/time/8-hour-shift/) | start time, paid hours and unpaid break | Shift ends at |
| [Minutes Between Two Times Calculator](/time/minutes-between-two-times/) | start time and end time | Minutes |
| [Work Calculator](/science/work-calculator/) | force, distance and angle between force and motion | Work |
Background: dates and times
Date and time results depend on the conventions a tool uses: whether the end date counts, whether weekends and holidays are skipped, how months of different lengths are handled and whether time zones are applied. This page states its convention, and the worked examples show it.
Dates use the Gregorian calendar and calendar days unless the page says otherwise; check deadlines against the rule in your contract or regulation.
Assumptions and limitations
- Break cannot exceed the shift
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for unpaid break and start time (24-hour) to confirm this.
Frequently asked questions
What is 8:45 to 17:15 with 45 minutes break?
8:45 to 17:15 is 8 h 30 min; minus a 45 minute break leaves 7:45.
Is the break paid?
No. The break is unpaid and subtracted from the time worked; enter 0 if your break is paid.
How do I total a week?
To total a week of work hours, add each day's result with the Add Times calculator.
What does the Work Hours Calculator calculate?
Hours worked between a start and end time minus breaks. It returns Time worked and Decimal hours.
What formula does the Work Hours Calculator use?
hours = (end − start) − break. Handles shifts that cross midnight.
What do I need to enter in the work Hours Calculator?
You enter Start time (24-hour), End time (24-hour) and Unpaid break (min).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Break cannot exceed the shift.
What is an example of a work Hours result?
With start time (24-hour) 09:00, end time (24-hour) 17:30 and unpaid break 30, the time worked is 8:00.
Related calculators
- Hours Calculator — Hours worked between a start and end time, minus breaks.
- Time From Now Calculator — Clock time after adding or subtracting minutes.
- Shift End Time Calculator — End time of a shift of a given length, including an unpaid break.
- Minutes Between Two Times Calculator — Minutes between two clock times, wrapping past midnight.
- Work Calculator — Work done by a force over a distance at an angle.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI): minute, hour and day are non-SI units accepted for use with the SI (60 min = 1 h, 24 h = 1 d)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.