Payroll mistakes on hourly teams usually come from time card math, not from bad intentions. Someone reads 8:52 AM to 5:17 PM as “about eight and a half hours,” a lunch break gets subtracted twice, or an overnight shift ends up as a negative number. These small errors add up across a team and a year, and they are easy to avoid once you have a repeatable method.
This guide shows you how to calculate hours worked step by step: converting clock times to decimal hours, subtracting unpaid breaks, handling shifts that cross midnight, and adding up the week so you can spot overtime. Every step comes with a worked example.
Why decimal hours matter
Clock times are written in hours and minutes (base 60), but pay rates are multiplied in decimals (base 10). If an employee worked 7 hours and 30 minutes, you can’t multiply 7.30 by their hourly rate. The correct figure is 7.5 hours. Writing 7.30 underpays that shift by 12 minutes’ worth of wages.
So the core rule is simple: convert minutes to a fraction of an hour by dividing by 60 before you multiply by a pay rate.
Step-by-step: how to calculate hours worked for one shift
Step 1: Write down the clock-in and clock-out times
Use the actual punch times from your time clock or timesheet. Note AM and PM carefully, because most errors on paper time cards start here.
Step 2: Convert both times to 24-hour format
Add 12 to any PM hour after 12:59 PM. For example, 5:17 PM becomes 17:17. Times from 12:00 AM to 12:59 AM become 0:00 to 0:59. This removes the AM/PM confusion and makes subtraction straightforward.
Step 3: Subtract the start time from the end time
Subtract hours from hours and minutes from minutes. If the end minutes are smaller than the start minutes, borrow 60 minutes from the hours column.
Step 4: Subtract unpaid breaks
Remove any unpaid meal period from the total. Under federal rules, short rest breaks (commonly 5 to 20 minutes) are generally counted as paid work time. Bona fide meal periods, typically 30 minutes or more where the employee is fully relieved of duties, are generally not counted. Some states have their own meal and rest break requirements, so check your state’s rules.
Step 5: Convert the remaining minutes to decimal
Divide the leftover minutes by 60 and add the result to the whole hours.
Worked example
An employee clocks in at 8:52 AM, clocks out at 5:17 PM, and takes an unpaid 30-minute lunch.
- Convert to 24-hour time: 8:52 and 17:17.
- Subtract: 17:17 minus 8:52. Since 17 minutes is less than 52, borrow an hour: 16:77 minus 8:52 = 8 hours 25 minutes.
- Subtract lunch: 8:25 minus 0:30 = 7 hours 55 minutes.
- Convert: 55 / 60 = 0.92 (rounded). Total = 7.92 hours.
If you would rather not do this by hand, the free time card calculator handles the conversion and break subtraction for you.
Minutes-to-decimal conversion table
Keep this table near whoever processes payroll. Values are rounded to two decimal places.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 1 | 0.02 | 31 | 0.52 |
| 5 | 0.08 | 35 | 0.58 |
| 6 | 0.10 | 36 | 0.60 |
| 10 | 0.17 | 40 | 0.67 |
| 12 | 0.20 | 42 | 0.70 |
| 15 | 0.25 | 45 | 0.75 |
| 18 | 0.30 | 48 | 0.80 |
| 20 | 0.33 | 50 | 0.83 |
| 24 | 0.40 | 54 | 0.90 |
| 25 | 0.42 | 55 | 0.92 |
| 30 | 0.50 | 60 | 1.00 |
Rounding to two decimals is standard. If you want maximum precision, keep three or four decimals until the final pay calculation, then round the dollar amount.
How to calculate overnight shifts
When a shift crosses midnight, a straight subtraction gives a negative number. There are two easy fixes.
Method 1: Split at midnight
Calculate the time from clock-in to midnight, then from midnight to clock-out, and add them.
Example: 10:00 PM to 6:30 AM with a 30-minute unpaid meal.
- 10:00 PM to 12:00 AM = 2 hours
- 12:00 AM to 6:30 AM = 6.5 hours
- Total = 8.5 hours, minus 0.5 hour meal = 8.0 hours
Method 2: Add 24 to the end time
Convert to 24-hour format and add 24 to the clock-out hour: 6:30 becomes 30:30. Then 30:30 minus 22:00 = 8:30, or 8.5 hours before the break.
One more detail for overnight work: assign the hours to the correct workweek. Under the FLSA, a workweek is a fixed, recurring period of 168 hours (seven consecutive 24-hour periods), and it doesn’t have to start on Sunday. If a shift straddles the boundary between two workweeks, the hours generally belong to the week in which they were actually worked. Decide how your business handles this and apply it consistently.
Adding up a weekly total
Once each day is in decimal hours, add them together for the workweek.
| Day | In | Out | Unpaid break | Hours |
|---|---|---|---|---|
| Monday | 8:52 AM | 5:17 PM | 30 min | 7.92 |
| Tuesday | 8:00 AM | 4:45 PM | 30 min | 8.25 |
| Wednesday | 7:30 AM | 4:30 PM | 30 min | 8.50 |
| Thursday | 7:00 AM | 4:30 PM | 30 min | 9.00 |
| Friday | 8:00 AM | 5:15 PM | 30 min | 8.75 |
| Saturday | 9:00 AM | 1:00 PM | None | 4.00 |
| Weekly total | 46.42 | |||
Calculating overtime from weekly hours
Under the federal Fair Labor Standards Act, non-exempt employees must receive at least 1.5 times their regular rate of pay for hours worked over 40 in a workweek. Some states add daily overtime rules or other requirements, so your state may be stricter. For a deeper look, read our guide to FLSA overtime rules.
Using the week above for an employee who earns $18.00 per hour:
- Regular hours: 40 x $18.00 = $720.00
- Overtime hours: 46.42 – 40 = 6.42
- Overtime rate: $18.00 x 1.5 = $27.00
- Overtime pay: 6.42 x $27.00 = $173.34
- Gross pay: $720.00 + $173.34 = $893.34
Keep in mind that the “regular rate” can include more than the base hourly wage, such as certain non-discretionary bonuses or shift differentials. The overtime calculator is a quick way to check your numbers.
This article is general information, not legal advice.
A note on rounding
Many employers round punches to the nearest 5, 6, or 15 minutes. Federal regulations allow rounding practices only if they are neutral over time, meaning they don’t consistently favor the employer. Some states and courts take a stricter view. If you round, apply the same rule in both directions. Our article on time clock rounding rules covers the details, including the 7-minute rule for 15-minute rounding.
Common time card math mistakes to avoid
- Treating minutes as decimals. 7:45 is 7.75 hours, not 7.45.
- Forgetting AM/PM. Convert to 24-hour time first.
- Deducting paid breaks. Short rest breaks are generally paid time under federal rules.
- Auto-deducting meals that didn’t happen. If an employee worked through lunch, that time must be paid.
- Averaging hours across two weeks. Overtime is calculated per workweek, not per pay period.
- Fixing missed punches by guessing. Use a documented correction process with employee and manager sign-off.
When to stop doing the math by hand
Manual calculation works for a handful of employees, and a free Excel timesheet template can take you a long way. As your team grows, the time spent checking punches, chasing missed clock-outs, and rechecking overtime starts to cost more than a tool would.
EZTime records clock-ins from a phone app, a shared tablet kiosk, SMS, or an NFC tag, and totals hours automatically. Managers get overtime alerts before an employee reaches 40 hours, missed-punch corrections go through an approval flow with an audit trail, and you can export payroll-ready reports to Excel or PDF. You can start a 14-day free trial with no credit card, or compare plans and pricing, which start at $2 per employee per month.
Frequently asked questions
How do I convert minutes to decimal hours?
Divide the minutes by 60. For example, 45 minutes divided by 60 equals 0.75, so 7 hours and 45 minutes is 7.75 hours. Round to two decimal places for most payroll purposes.
Are breaks included in hours worked?
Under federal rules, short rest breaks of about 5 to 20 minutes are generally counted as hours worked and paid. Bona fide meal periods, usually 30 minutes or more where the employee is fully relieved of duty, generally are not. State rules may add requirements.
How do I calculate hours for a shift that goes past midnight?
Either split the shift at midnight and add the two parts, or convert to 24-hour time and add 24 to the clock-out hour before subtracting. A 10:00 PM to 6:30 AM shift equals 8.5 hours before any unpaid break.
Is overtime calculated per day or per week?
Federal law requires overtime for hours over 40 in a workweek. A few states, such as California, also have daily overtime rules. Check your state’s requirements in addition to the FLSA.
What’s the fastest way to total weekly hours for my team?
Use a digital time clock that records punches and calculates totals automatically. For occasional checks, a time card calculator or spreadsheet template works well for small teams.