Punch Clock MathHours, overtime and every state’s rules

22 guides · 4 in depth · updated October 22, 2026

Guides, one question each

Each guide answers one question with the rule from the law or the agency that enforces it, works it through on real numbers and lists its sources with the date they were read.

Hours & time cards

Adding up a time card the right way: minutes and decimal hours, breaks, overnight shifts, daylight saving time and 24-hour clocks — worked through on real examples.

All 5 on one page

Calculators: Time card · Hours · Time to decimal · Add hours · Military time

Overtime rules

The federal 40-hour rule and every state rule on top of it — daily overtime, seventh-day overtime, double time — plus the regular rate, bonuses and who is exempt, each from the law or the agency that enforces it.

All 9 on one page

Calculators: Overtime · Time card · Regular rate

Pay & the overtime deduction

Hourly to salary, raises, and the 2025–2028 federal deduction for overtime pay: what counts, the cap and the income limit, and how to find your number — from the law and the IRS.

All 4 on one page

Calculators: No tax on overtime · Hourly to salary · Salary to hourly · Pay raise · Gross pay

Rules & records

Breaks, time-clock rounding, the records employers must keep and the federal holiday calendar — what the rules say and what to check on your own time card.

All 4 on one page

Calculators: Rounding · Business days · PTO accrual · Hours in a year