How the hours are worked out
Each day is the time between clocking in and clocking out, minus any break you were not paid for. If the end time is earlier than the start time the shift is treated as crossing midnight, so 22:00 to 06:00 is eight hours rather than a negative number.
If your employer rounds punches, set the same rounding here. Federal rules permit rounding to the nearest 5, 6 or 15 minutes as long as it does not consistently favour the employer — the key word being nearest. Rounding that always goes down is not permitted, and a pattern of it is worth raising.
A worked example
Four days of 9:00 to 17:30 with a 30-minute unpaid lunch, one day of 9:00 to 18:30 with the same break:
- Each 9:00–17:30 day is 8 hours 30 minutes, less 30 minutes, so 8 hours.
- The 9:00–18:30 day is 9 hours 30 minutes, less 30 minutes, so 9 hours.
- The week totals 41 hours.
Under the federal rule that is 40 regular and 1 hour of overtime. In California the nine-hour day produces 1 hour of daily overtime, leaving 40 regular — the same answer by a different route. The routes diverge as soon as the days get longer.
Daily and weekly overtime, and the trap between them
Federal law counts overtime weekly: anything over 40 hours in a workweek is paid at time and a half. A single fourteen-hour day inside a 38-hour week is not overtime at all, which surprises people and is correct.
Some states add a daily rule. California is the strictest: over 8 hours in a day is time and a half, over 12 is double time, and the seventh consecutive day worked in a workweek is premium from the first hour.
Where it goes wrong: five ten-hour days is 50 hours. The daily rule gives 2 overtime hours a day, so 10 in total, leaving 40 regular. The weekly over-40 rule then applies to nothing, because those 10 hours have already been counted. A calculator that adds both reports 20 overtime hours — double the real figure. This one applies the weekly threshold only to hours that are still regular after the daily rules have run, and says so underneath the result.
What this does not do
- It does not deduct tax. The pay figure is gross — before income tax, payroll tax and any deductions. Your take-home will be lower.
- It does not know your employment classification. Overtime rules apply to non-exempt employees. If you are salaried and exempt, or an independent contractor, the overtime figures do not apply to you.
- It does not model every state. Only the states with a genuinely different daily rule are listed. Everywhere else the federal weekly rule is the whole story, and inventing state variation would be inventing precision.
- It does not handle shift differentials, tips, or piece rates, all of which change the regular rate that overtime is calculated from.
- It is not legal advice. If you believe you have been underpaid, your state labour department is free and takes complaints.
Common questions
How do I calculate hours worked with a lunch break?
Take the time between clocking in and out, then subtract the break if it was unpaid. A 9:00 to 17:30 shift is 8 hours 30 minutes; with an unpaid 30-minute lunch you were paid for 8 hours. If the break was paid, do not subtract it.
Is overtime daily or weekly?
Federally, weekly — over 40 hours in a workweek. California, Alaska, Nevada and Colorado add a daily threshold. Choosing your state above applies the right one and names it under the result.
Can my employer round my clock-in time?
Within limits. Rounding to the nearest 5, 6 or 15 minutes is permitted provided it does not systematically favour the employer. Rounding that always lands in the employer's favour is not lawful, and if your punches are consistently rounded down it is worth documenting.
What is a workweek?
A fixed, recurring period of 168 consecutive hours — seven consecutive 24-hour days. Your employer sets when it starts, and it does not have to match the calendar week. Overtime is calculated within it, which is why hours cannot be averaged across two weeks to avoid paying it.
References
- US Department of Labor — overtime pay, the federal 40-hour rule.
- 29 CFR Part 778, how overtime compensation is computed, including rounding.
- California DIR — overtime, the daily, double-time and seventh-day rules.