There are 168 hours in a week. Seven days times twenty-four. That part takes one line.
The reason you are probably here is the next question — how many work hours that turns into over a month or a year — and that is where the tidy numbers stop working. Multiply 40 hours by 4 weeks for a month and you are short by nearly 14 hours. Multiply 40 by 52 weeks for a year and you get 2,080, which the US government looked at, studied for a full calendar cycle, and formally abandoned in 1984.
Here are all the numbers, and the three places the easy arithmetic quietly costs people money.
The Plain Answers
| Period | Total hours |
|---|---|
| A day | 24 |
| A week | 168 |
| A fortnight (two weeks) | 336 |
| February (28 days) | 672 |
| February (29 days, leap) | 696 |
| A 30-day month | 720 |
| A 31-day month | 744 |
| An average month | 730.5 |
| A common year | 8,760 |
| A leap year | 8,784 |
The average month is 730.5 hours because the average month is 30.4375 days — that is 365.25 divided by 12, using 365.25 to account for leap years. There is no month that is actually 730.5 hours long, but it is the right figure to use whenever you are spreading something evenly across a year.
A Month Is Not Four Weeks
This is the most common and most expensive mistake in the whole subject.
Four weeks is 28 days. The only month that short is February, and in a leap year not even February. Every other month is 30 or 31, so "four weeks" falls two or three days short, every single month.
Work it out properly. A year has 365.25 days, which is 52.1786 weeks, which spread across 12 months is 4.3482 weeks per month — not 4.
| Working 40 hours a week | Hours per month |
|---|---|
| 40 × 4 weeks (the shortcut) | 160.00 |
| 40 × 4.3482 weeks (actual average) | 173.93 |
| Difference | 13.93 hours every month |
Nearly fourteen hours a month. Over a year that is 167 hours — more than four full working weeks — simply unaccounted for by a habit of rounding a month to four weeks.
If you are quoting a monthly rate, budgeting contractor cost, or checking whether a salary matches an hourly figure, 160 is the wrong number. Use 173.33 (which is 2,080 ÷ 12) or 173.93, depending on which annual figure you start from — and the next section is about exactly that choice.
Why Payroll Uses 2,087 Hours
Ask almost anyone how many work hours are in a year and you will hear 2,080 — 52 weeks times 40 hours. It is the number in most spreadsheets and most salary conversations.
It is also slightly wrong, and the reason is simple: 52 weeks is 364 days. A year is 365 or 366. Every year quietly contains an extra day or two that the 52-week model never counts.
The US Office of Personnel Management used to divide annual salaries by 2,080. Then a 1981 study by the General Accounting Office counted the actual working days across a full 28-year calendar cycle — the span over which the pattern of weekdays repeats, as long as it does not cross a skipped leap year like 1900 or 2100 — and found the true average was 2,087 hours. Since 1984, federal hourly rates have been computed with the 2,087 divisor instead.
The practical effect is small per hour and real over a career. On a $75,000 salary, dividing by 2,080 gives $36.0577 an hour; dividing by 2,087 gives $35.9368. About twelve cents. That twelve cents then gets multiplied by every overtime hour you ever work, which is precisely why the divisor is written into policy rather than left to whoever is building the spreadsheet.
The Year You Get an Extra Paycheck
The same missing day produces a much more visible effect if you are paid every two weeks.
Twenty-six biweekly pay periods cover 26 × 14 = 364 days. A common year is 365, a leap year 366. So every year leaves one or two days unpaid by the 26-period model, and those days accumulate.
Roughly every eleven years, the leftovers add up to a whole extra pay period and you receive 27 paychecks instead of 26 — or 53 instead of 52 if you are paid weekly.
Turning 7:45 Into 7.75
Now the mistake that shows up on individual timesheets rather than annual figures.
Clock time is base 60 — sixty minutes to the hour. Payroll is decimal, because it multiplies your hours by your rate. Those are two different number systems, and moving between them by eye goes wrong constantly.
A shift of 7 hours 45 minutes is 7.75 hours, not 7.45. Writing 7.45 shortens the shift by 18 minutes. Do that every day and it is exactly an hour and a half across a five-day week.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 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 |
The rule is just minutes ÷ 60. Of the values above, only 15, 30 and 45 divide into exact decimals — every other row is rounded to two places. That is why those three feel familiar and the rest get guessed at.
What Actually Counts as Overtime
Two details trip people up more than the rate itself.
Overtime is usually weekly, not daily. Under the US Fair Labor Standards Act the standard threshold is 40 hours in a workweek, so a ten-hour Monday is not automatically overtime — it only becomes overtime if the week's total passes 40. Some states and many countries add a daily rule on top, and contracts can set their own.
"Time and a half" means 1.5× the hourly rate for the extra hours only. On a 45-hour week at $20, the first 40 hours pay $800 and the extra 5 pay $30 each — $150 — for $950 total. It is not the whole week at the higher rate.
And unpaid breaks come off before any of this. A 30-minute unpaid lunch across five days removes 2.5 hours from the week, which can be the difference between finishing at 40 hours and finishing at 37.5.
Working Out Your Own Hours
- Open the Time Card Calculator and enter your clock in and clock out times for each day.
- Add unpaid breaks in minutes. They are subtracted from that day before anything else is worked out.
- Read both totals. The hours and minutes figure is for you; the decimal figure is the one payroll wants.
- Set the overtime threshold and multiplier to match your contract. The defaults are 40 hours at 1.5×, but neither is universal.
- Add your hourly rate to see regular pay and overtime pay separately, so you can check the split rather than just the total.
Night shifts are handled — a clock out earlier than the clock in is treated as crossing midnight, so 22:00 to 06:00 counts as 8 hours rather than a negative number.
Nothing is uploaded. The whole calculation happens inside the page, which matters here because a timesheet quietly reveals both your schedule and your earnings.