Calculating how many hours you have worked sounds simple — until you factor in unpaid lunch breaks, overnight shifts, split working days, and overtime thresholds that vary by jurisdiction. Getting the math wrong costs money: underpaid employees, overbilled clients, or incorrect payroll submissions. This guide explains every aspect of hours worked calculation — manual formulas, decimal conversion, break deductions, and overtime rules — and shows you how the free Work Hours Calculator handles all of it in seconds.
How to calculate hours worked
The core formula for calculating hours worked is straightforward: subtract your start time from your end time, then deduct any unpaid break time. The result is your net paid hours for that shift. For example, clocking in at 9:00 AM and out at 5:30 PM gives 8.5 gross hours. Deduct a 30-minute unpaid lunch and you have 8.0 net paid hours. For a full week, sum each day's net hours to get the weekly total.
Manual calculation in 24-hour format
Converting both times to 24-hour format before subtracting avoids AM/PM confusion. 9:00 AM becomes 09:00; 5:30 PM becomes 17:30. Subtract: 17:30 minus 09:00 = 8 hours 30 minutes = 8.5 hours. For overnight shifts, add 24 to the end time before subtracting — a 10:00 PM to 6:00 AM shift becomes 30:00 minus 22:00 = 8 hours. This rule handles every shift cleanly without needing special-case logic.
When clock-in and clock-out times span days
Some industries — healthcare, hospitality, logistics — regularly schedule shifts that span midnight. The calculation is the same: always add 24 hours to the end time when it is earlier than the start time. A 23:00 to 07:00 shift is 07:00 + 24:00 = 31:00, then 31:00 minus 23:00 = 8 hours. The Time Duration Calculator handles this automatically with its overnight rollover toggle — no mental arithmetic required.
- Standard day shift: End time minus start time minus unpaid breaks = net hours.
- Overnight shift: Add 24 to end time, then subtract start time, then deduct breaks.
- Split shift: Calculate each segment separately, sum the segments, then deduct total breaks.
- Multiple days: Calculate each day individually and sum for the weekly total.
Note
Decimal hours and time conversion
Payroll systems, invoicing software, and most spreadsheet formulas require hours expressed as a decimal number — not hours and minutes. Multiplying an hourly rate by "8h 45m" gives a wrong result; multiplying by 8.75 gives the correct one. Converting between hours:minutes and decimal hours is a single calculation, but it is easy to get wrong under time pressure.
One minute equals 1/60 of an hour. Every minutes-to-decimal conversion follows the same rule: divide minutes by 60 and add to whole hours.
Converting minutes to decimal hours
Divide the minutes portion by 60, then add the result to the whole hours. Examples: 7h 30m = 7 + (30 ÷ 60) = 7.50. 8h 20m = 8 + (20 ÷ 60) = 8.33. 6h 45m = 6 + (45 ÷ 60) = 6.75. 9h 15m = 9 + (15 ÷ 60) = 9.25. These four — 0.25, 0.33, 0.50, 0.75 — are the most common decimal fractions in time tracking.
| Time (h:mm) | Decimal Hours | Calculation |
|---|---|---|
| 7:15 | 7.25 | 7 + 15÷60 |
| 7:30 | 7.50 | 7 + 30÷60 |
| 7:45 | 7.75 | 7 + 45÷60 |
| 8:20 | 8.33 | 8 + 20÷60 |
| 8:40 | 8.67 | 8 + 40÷60 |
| 9:10 | 9.17 | 9 + 10÷60 |
| 10:00 | 10.00 | Whole hour |
Converting decimal hours back to hours:minutes
Reverse the process: take the decimal portion and multiply by 60 to get minutes. 8.75 hours = 8 whole hours + (0.75 × 60) = 8 hours 45 minutes. 8.33 hours = 8 hours + (0.33 × 60) = 8 hours 20 minutes. The Work Hours Calculator displays both formats simultaneously for every entry — you never have to convert manually when using the tool.
Tip
How to use the hours worked calculator
The Work Hours Calculator on Quasar Tools handles every scenario covered in this guide — single shifts, multi-day timesheets, overnight crossovers, break deductions, overtime flagging, and gross pay estimation. It runs entirely in your browser: no account, no upload, no data leaving your device.
Enter start and end times for each day
Open the Work Hours Calculator and enter clock-in and clock-out times for each working day. Both 12-hour AM/PM (e.g., 9:00 AM, 5:30 PM) and 24-hour formats (09:00, 17:30) are accepted. Add a new row for each additional day to build a full-week timesheet or multi-week payroll period.
Add unpaid break deductions per day
Enter the total unpaid break time in minutes for each day. The calculator subtracts the break from gross worked time automatically to give you net paid hours. If your breaks vary daily — 45 minutes Monday, 30 minutes Tuesday — enter each separately. Paid rest breaks should not be included in this field; only deduct time for which you are not being paid.
Set overtime thresholds
Enter your regular daily hours threshold (typically 8) and weekly threshold (typically 40). Any net hours above the daily limit are flagged as daily overtime. Any cumulative weekly hours above the weekly limit — after daily overtime is already accounted for — are flagged as weekly overtime. Both totals are shown separately so you can verify the breakdown.
Enter hourly rate for gross pay estimation
Enter your base hourly rate and overtime multiplier to see a gross pay estimate. Regular hours are multiplied by the base rate; overtime hours are multiplied by the base rate times the multiplier. The result is an estimated gross pay — before taxes, deductions, and employer contributions. This figure is useful for invoice generation, payroll verification, and client billing reconciliation.
Work Hours Calculator
Calculate total hours worked, break deductions, daily and weekly overtime, and gross pay estimation — free, browser-local, handles overnight shifts and split days.
Breaks and unpaid time deductions
Not all time at work is paid time. The distinction between paid and unpaid breaks determines whether break time is included in hours worked — and therefore in overtime calculations, minimum wage compliance, and payroll totals. Getting this wrong understates or overstates hours worked.
Paid rest breaks vs unpaid meal breaks
Paid rest breaks — typically 10 to 15 minutes for every 4-hour work period in the US, UK, and most of Europe — count as hours worked. You remain "on the clock" and the time flows into your total. Unpaid meal breaks — typically 30 to 60 minutes — do not count as hours worked, provided the employee is fully relieved of duties. If an employee must remain at their desk or be available for urgent tasks during lunch, that break becomes compensable time in most jurisdictions.
How break deductions affect overtime
Deducting breaks before applying overtime thresholds is correct. If a shift runs 9 hours on the clock but includes a 1-hour unpaid lunch, net hours are 8 — below the 8-hour daily overtime threshold in most contracts. If breaks are ignored and the full 9 hours are counted, overtime would appear to be triggered. Applying the break deduction first prevents phantom overtime entries in the timesheet.
- Paid 10–15 min rest breaks: Count toward hours worked — do not deduct.
- Unpaid 30–60 min meal breaks: Deduct from gross hours — employee must be fully relieved.
- On-call meal breaks: If the employee cannot leave and must respond to calls, this break is likely compensable — do not deduct.
- Travel time between sites: Compensable in most jurisdictions — count toward hours worked.
- Pre-shift setup time: If required by employer, generally compensable — count toward hours worked.
Warning
Overtime calculation rules
Overtime rules vary significantly by country, state, and employment contract. Understanding the applicable threshold and rate before calculating overtime pay prevents underpayment errors that can result in legal liability and back-pay claims.
Daily vs weekly overtime thresholds
Some jurisdictions apply daily overtime (any hours above 8 in a single day trigger overtime regardless of weekly total). Others apply only weekly overtime (no overtime until the weekly total exceeds 40 hours). California, for example, applies both: daily overtime at 8 hours and double time at 12 hours per day, plus weekly overtime at 40 hours. Federal US law (FLSA) only mandates weekly overtime at 40 hours. Always check the specific rule for your location and industry.
| Jurisdiction | Daily OT Threshold | Weekly OT Threshold | OT Rate |
|---|---|---|---|
| US Federal (FLSA) | None | 40 hours | 1.5× |
| California | 8 hours | 40 hours | 1.5× (2× above 12h/day) |
| United Kingdom | None | 48 hours (avg) | Contract-defined |
| Canada (federal) | None | 40 hours | 1.5× |
| Australia | None | 38 hours | 1.5× (2× after 3h OT) |
| Germany | None | 48 hours | Contract-defined |
Calculating overtime pay amounts
Multiply overtime hours by the base hourly rate, then by the overtime multiplier. At $20/hour with 3 hours of overtime at 1.5×: 3 × $20 × 1.5 = $90 overtime pay, plus the regular pay for the first 40 hours. The Work Hours Calculator separates regular hours and overtime hours in the output and calculates both pay components independently — giving you a clear audit trail for every payroll submission.
Salaried employees and overtime
Salaried employees classified as exempt from overtime — typically those earning above a salary threshold (US $684/week federal minimum) in an executive, administrative, or professional role — do not receive overtime pay regardless of hours worked. Non-exempt salaried employees do receive overtime pay for hours above the threshold; their regular rate is calculated as weekly salary divided by hours worked, and overtime is 1.5× that rate. Misclassifying non-exempt employees as exempt is one of the most common US wage-and-hour violations.
Tip
Hours worked by use case
The calculation is the same regardless of context — but what you do with the result varies by situation. These are the most common use cases and what to pay attention to in each.
Employee timesheets and payroll
For payroll, net paid hours drive gross wages. Calculate each employee's daily net hours, verify overtime flags against the applicable rule for their location, and submit totals to payroll for the pay period. For biweekly payroll (26 periods per year), each period covers two work weeks; calculate weekly overtime separately for each week within the period — combining both weeks into a single 80-hour total would incorrectly average out overtime that was legitimately earned in one week.
Freelance and contractor billing
Freelancers bill by tracked hours. Log each session's start and end time with a description, apply break deductions for any unpaid interruptions, and sum billable hours for the invoice period. The Work Hours Calculator with your billing rate entered gives a gross invoice amount directly. For calculating how many working days fall in a billing month, use the Business Days Calculator alongside the hours tracker.
Project time tracking and client reporting
Project managers tracking billable hours across multiple projects need daily totals per project, not just total hours worked. Log each project block separately, then sum per project for the weekly or monthly report. Convert all totals to decimal hours before entering a spreadsheet — it makes formula-based aggregation reliable. Total hours across all projects should equal total hours worked for the period; if they do not, time was either double-counted or unaccounted.
SLA verification and compliance
Service Level Agreements sometimes measure response times in business hours rather than calendar hours. If a ticket was opened at 4:30 PM Friday on a day your office closes at 5:00 PM, a "4 business-hour SLA" only uses 30 minutes of that Friday — the remaining 3.5 hours carry over to Monday morning. For these calculations, combine the Time Duration Calculator (for within-day durations) with the Business Days Calculator (to account for non-working days in the SLA window).
Key takeaways
- Net hours worked = (End time minus start time) minus unpaid breaks — always work in 24-hour format to avoid AM/PM errors.
- For overnight shifts, add 24 to the end time before subtracting the start time — e.g., 22:00 to 06:00 is 30:00 minus 22:00 = 8 hours.
- Convert to decimal hours for payroll: divide the minutes by 60 and add to whole hours (7h 45m = 7.75).
- Only deduct truly unpaid breaks — paid rest breaks count toward hours worked and toward overtime thresholds.
- Overtime rules vary by jurisdiction: US federal law triggers at 40 hours per week; California adds daily overtime at 8 hours; UK averages 48 hours per week.
- The Work Hours Calculator on Quasar Tools handles breaks, overnight shifts, daily and weekly overtime thresholds, and gross pay estimation — free, browser-local, no signup.
- For adjacent calculations, use the Time Duration Calculator for single-shift timing, the Business Days Calculator for payroll period working-day counts, and the Date Difference Calculator for calendar day spans.