About Punch Clock Math
Free calculators for time cards, hours and overtime that know each state’s rules, with every rule dated and sourced.
What this site is
Punch Clock Math adds up time cards and hours the way payroll does — in whole minutes, across midnight and on daylight-saving nights — and splits the hours into regular time and overtime under the federal rule and each state’s own rules, for all 50 states and DC. It has 16 calculators, 22 guides, and two reference tables: overtime laws by state and break laws by state.
It is written for hourly workers checking their own time and pay, mostly on a phone right after a shift, and for the owners and managers of small businesses who add up time cards and run payroll themselves.
Who runs it
Punch Clock Math is an independent site run by an individual based in the United States. The site’s author and publisher is Punch Clock Math itself; no guide carries a personal byline. It has no employees, no investors and no relationship with any employer, payroll company, law firm, tax preparer or agency.
Punch Clock Math is an independent website. It is not a law firm, a payroll company, a tax preparer or a government agency, and it is not affiliated with, endorsed by or sponsored by the U.S. Department of Labor, the IRS, any state agency or any company named on this site. Names are used only to identify sources.
How the numbers are checked
- Every rule comes from a primary source: the U.S. Code, the eCFR, the Department of Labor, the IRS, or the state’s own labor department, statutes or code. The site holds 440 such sources today, each with the date it was read and the sentence it was read for, on the data page.
- Each of the 51 state rows was read from that state’s own pages and then re-checked independently. A rule that could not be confirmed is marked “not confirmed”, never guessed.
- The calculators run on tested engines: time in whole minutes, money in whole cents rounded once per line, and hundreds of worked examples (overnight shifts, daylight-saving nights, daily and weekly overtime in the same week, every state’s rule) that must pass before the site is built.
- Every change of a value is logged with its date on the updates page; the site will not build if a value changes without a log entry. Sources last checked October 22, 2026.
Guides are drafted with AI writing tools, then every number in them is recomputed with the same engines the calculators use, and every statement is checked against the sources listed under the guide. See the Editorial Policy.
Your privacy
No sign-up, no forms, no analytics. What you type into a calculator stays in your browser; a time card you keep is saved on your own device and nowhere else. Details are in the Privacy Policy.
How it is paid for
Punch Clock Math is free to use and will be paid for by advertising. No employer, payroll company, law firm or agency pays for anything on this site. Ads are kept away from the calculators and their results, and they never change what a page says.
Contact
Corrections, broken links and questions about how a number was computed: hello@punchclockmath.com. We can’t advise on individual cases; see the contact page for who can.