How hours are counted
Convert both times to minutes since midnight, subtract, and if the result is negative the shift crossed midnight, so add 24 hours. Take off any unpaid break, then express the remainder as hours and minutes or divide by 60 for decimal hours. 9:00 AM to 5:30 PM is 510 minutes; less a 30-minute lunch, 480 minutes, which is 8:00 or 8.00 hours.
The table shows common shifts, including two overnight ones.
| Shift | Break (min) | Hours:minutes | Decimal hours |
|---|---|---|---|
| 9:00 AM – 5:00 PM | 30 | 7:30 | 7.50 |
| 8:30 AM – 5:15 PM | 45 | 8:00 | 8.00 |
| 7:00 AM – 3:30 PM | 30 | 8:00 | 8.00 |
| 10:00 PM – 6:00 AM | 30 | 7:30 | 7.50 |
| 11:00 PM – 7:30 AM | 60 | 7:30 | 7.50 |
| 6:00 AM – 2:00 PM | 0 | 8:00 | 8.00 |
Minutes to decimal hours
Payroll systems multiply decimal hours by the hourly rate, so 7 hours 30 minutes must be entered as 7.50, not 7.30 — a common and costly mix-up. Decimal hours = minutes ÷ 60. The table converts every 5 minutes; for exact values, 1 minute is 0.0167 hours.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 0 | 0.00 | 30 | 0.50 |
| 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 |
| 60 | 1.00 |
Rounding time entries
US federal rules allow employers to round clock-in and clock-out times to the nearest 5, 10 or 15 minutes provided the rounding is neutral over time — it cannot always favour the employer. Under the common '7-minute rule' for quarter-hour rounding, 1–7 minutes past the quarter round down and 8–14 round up. The calculator uses exact minutes; apply your workplace's rounding if it has one.
| Rounds down | Rounds up | Rounds up |
|---|---|---|
| 9:03 → 9:00 | 9:07 → 9:15 | 9:08 → 9:15 |
| 9:22 → 9:15 | 9:23 → 9:30 | 9:38 → 9:45 |
| Round to nearest 15 min; 7 min or less rounds down |
Adding up a week
For several shifts, work out each day's decimal hours and add them. The time card calculator does this for a full week with overtime; here is what the arithmetic looks like.
| Day | Shift | Break (min) | Hours |
|---|---|---|---|
| Monday | 9:00 AM – 5:30 PM | 30 | 8.00 |
| Tuesday | 9:00 AM – 6:00 PM | 30 | 8.50 |
| Wednesday | 8:00 AM – 4:30 PM | 45 | 7.75 |
| Thursday | 9:00 AM – 7:00 PM | 60 | 9.00 |
| Friday | 9:00 AM – 3:00 PM | 30 | 5.50 |
| Total | 38.75 |
Breaks and what counts as work time
In the US, short rest breaks of 5–20 minutes are counted as paid work time under federal law; meal breaks of 30 minutes or more can be unpaid if the worker is fully relieved of duty. State rules vary (California, for example, requires a 30-minute meal break after 5 hours). Enter only unpaid break time in the calculator; paid breaks are simply part of the shift. Time spent on call, travelling between job sites during the day, or in required training is usually paid time too.
Hours in a day, week, month and year
Useful reference figures for planning and payroll: a full-time week is 40 hours; a month averages 173.3 working hours (2,080 ÷ 12); a year has 2,080 working hours at 40 a week, or 1,880 after 25 days off. A calendar day has 1,440 minutes and a week 10,080; a 31-day month has 744 hours and a year 8,760 (8,784 in a leap year). Part-time and compressed schedules scale accordingly: a 4-day, 10-hour week is still 40 hours; a 0.6 FTE post is 24 hours a week and 1,248 a year.
| Span | Calendar hours | Working hours (40 h/week) |
|---|---|---|
| Day | 24 | 8 |
| Week | 168 | 40 |
| Month (average) | 730.5 | 173.3 |
| Quarter | 2,191 | 520 |
| Year | 8,760 | 2,080 |
| Year after 25 days off | — | 1,880 |
Overnight shifts and time formats
When the end time is earlier than the start, the calculator assumes the shift ended the next day — 10:00 PM to 6:00 AM is 8 hours, not −16. Both 12-hour (5:30 PM) and 24-hour (17:30) formats are accepted, with or without minutes. For durations spanning more than a day, or from one date-time to another, the time duration calculator takes dates as well.