How to calculate hours worked, step by step
A time card looks simple, but most payroll disputes start with a small arithmetic slip: someone subtracts 8:45 from 17:30 as if minutes were decimals, or forgets that a lunch break was unpaid. Here is the method the calculator uses, written out so you can check any day by hand.
- Write both times in 24-hour form. 9:15 am stays 9:15; 5:40 pm becomes 17:40. If you prefer 12-hour times, the calculator accepts "9:15am" and "5:40pm" when "Type times as text" is on.
- Subtract the start from the end, hours and minutes separately. 17:40 minus 9:15 is 8 hours and 25 minutes. When the end minutes are smaller than the start minutes, borrow an hour: 17:10 minus 9:15 is 7 hours 55 minutes (borrow 60 minutes, so 16:70 minus 9:15).
- Subtract unpaid breaks. With a 30-minute unpaid lunch, 8 hours 25 minutes becomes 7 hours 55 minutes.
- Convert to decimal hours for payroll. Divide the minutes by 60: 55 / 60 = 0.917, so the day is 7.92 hours. At $18 per hour that is $142.50.
- Repeat for each day and add the results. Add hours and minutes in their own columns, then carry every 60 minutes into an extra hour.
Worked example. Monday to Friday, 8:30 am to 5:00 pm with a 45-minute unpaid lunch. Each day spans 8 hours 30 minutes, minus 45 minutes, which leaves 7 hours 45 minutes, or 7.75 hours. Five days total 38 hours 45 minutes, or 38.75 hours. No overtime is owed under a 40-hour weekly rule, and at $22 per hour gross pay is 38.75 × 22 = $852.50.
How lunch and rest breaks are deducted
Only unpaid breaks are subtracted. Whether a break is paid depends on your employer's policy and, in the US, on the Fair Labor Standards Act (FLSA) rules on what counts as hours worked. As a rule of thumb under federal guidance, short rest breaks of about 5 to 20 minutes are treated as compensable working time and stay on the clock, while a bona fide meal period, typically 30 minutes or longer, is not paid as long as you are completely relieved of duty. A lunch spent answering phones at your desk is working time. Several states go further and require meal breaks after a set number of hours; California, for example, requires a 30-minute meal period for shifts over five hours. If your break is paid, set the break minutes to 0 for that row so it is not deducted.
Minutes to decimal hours
Payroll software wants decimal hours, so 7 hours 45 minutes is entered as 7.75, not 7.45. The conversion is minutes divided by 60. The quarter-hour marks are the ones people remember; the rest are on the full 1-to-60-minute chart.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.08 | 35 | 0.58 |
| 10 | 0.17 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 25 | 0.42 | 55 | 0.92 |
| 30 | 0.50 | 60 | 1.00 |
Overtime basics
Under the FLSA, non-exempt employees in the US earn overtime at one and a half times their regular rate for hours worked over 40 in a single workweek. The workweek is a fixed, recurring block of 168 hours; it does not have to run Monday to Sunday, but it cannot be averaged with the week before or after. That is why the biweekly option on this calculator applies the threshold to each week separately.
Some states add a daily threshold on top of the federal weekly one. As of the verification date below: California requires overtime after 8 hours in a day (and double time after 12), Alaska and Nevada after 8 hours in a day (Nevada's daily rule applies only to workers earning below a wage threshold), and Colorado after 12 hours in a day. Set "Daily OT after" to 8 or 12 to model these; the calculator counts daily overtime first, then applies the weekly threshold to the remaining regular hours so no hour is counted twice. Rules change and carry exceptions for industries, union agreements, and alternative workweek schedules, so check your state labor department's current guidance before relying on a figure.
Figures verified 2026-09-15. Federal 40-hour weekly threshold and 1.5× rate: 29 U.S.C. § 207. Break guidance: 29 C.F.R. § 785.18 and § 785.19. Rounding: 29 C.F.R. § 785.48(b). State daily-overtime rules as published by the California, Alaska, Nevada, and Colorado labor agencies on that date.
The 7-minute rounding rule
Federal regulations allow employers to round clock-in and clock-out times to the nearest 5 minutes, tenth of an hour (6 minutes), or quarter hour (15 minutes), provided the practice does not, over time, fail to pay employees for all the time they actually work. Quarter-hour rounding produces the "7-minute rule": a punch 1 to 7 minutes past a quarter-hour mark rounds down, and 8 to 14 minutes rounds up. Clocking in at 8:07 is treated as 8:00; clocking in at 8:08 is treated as 8:15. Over many punches this should average out. If it consistently favors the employer, it is not permitted. This calculator applies rounding to each day's worked total; some employers round each punch instead, which can differ by a few minutes on a given day.
Common time card mistakes
- Treating minutes as decimals. 8:45 is 8.75 hours, not 8.45. Fifteen minutes of pay disappears every time this happens.
- Deducting a paid break. If your employer pays for a 15-minute rest break, it should not come off your hours.
- Forgetting the overnight roll-over. 22:00 to 06:00 is 8 hours, not negative 16. The calculator handles this; a spreadsheet often will not.
- Averaging overtime across a pay period. 45 hours plus 35 hours is not 80 regular hours. The 5 extra hours in week one are overtime.
- Mixing up am and pm. A 5:00 am end time on a day shift is almost always a typo for 5:00 pm. The calculator flags days over 16 hours so you can catch it.
- Rounding the weekly total instead of each day. Rounding rules apply to punches or days; rounding a 39.9-hour week to 40 is not how any of the permitted methods work.