ShiftDifferentialCalculator.com is a free set of pay calculators and plain-English guides for hourly workers, nurses, security staff, warehouse and call-center employees, and the payroll teams who pay them. It was built because shift pay is easy to get wrong: a night, weekend or holiday premium looks simple on its own, but it changes how overtime has to be calculated.
You can use the site to estimate a paycheck, to check whether overtime was calculated on the right rate, or simply to understand what the lines on your pay stub mean.
The site has six calculators: a general shift differential calculator, plus focused tools for night shifts, weekends, holidays, time and a half and double time. The blog explains the rules behind them, including the federal overtime rule and how California, New York and Texas treat shift pay.
Our main calculator follows the federal “regular rate of pay” method (29 CFR § 778.207). Shift differentials are treated as extra premium on the hours they cover. The weekly regular rate is then total straight-time pay, including those premiums, divided by total hours worked. Overtime and double-time premiums are calculated on that blended rate rather than on the base wage alone. Every step is shown in the results panel so you can verify it, and our overtime guide walks through worked examples.
Your inputs are processed in your browser and are never sent to our servers. Results are estimates: daily overtime rules, union contracts and employer policies can change what you are actually owed.
Every guide is written and maintained by the ShiftDifferentialCalculator.com editorial team. We build our articles on primary sources: the U.S. Department of Labor Wage and Hour Division, the Code of Federal Regulations (29 CFR Part 778), the IRS, and the labor departments of the states we cover. Where we give an example, we show the arithmetic so you can check it yourself.
Each article shows the date it was published. When a rule changes, or when a reader reports an error, we correct the page and update the date. We do not accept payment to change what our guides or calculators say, and nothing on this site is legal, tax or payroll advice. See our Disclaimer.
Before a guide or calculator goes live, it goes through the same five steps:
We link to the sources behind our explanations so you can read the rule yourself:
Labor rules change. We re-check our calculators and guides against current Department of Labor guidance at least twice a year, and sooner when we learn of a change or a reader reports a problem. If we correct an article, we fix the page itself rather than leaving the old wording in place, and we update its date.
Our guides are written for hourly employees, payroll staff and small employers in the United States. We explain how the federal rules generally work and show examples from several states. We cannot account for your contract, your employer’s policy or every local ordinance, so treat our results as a starting point for a conversation with payroll, HR or a qualified professional.
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Found a mistake, a broken calculation or an outdated rule? Email [email protected] or use the contact form. We read every message and fix confirmed errors promptly.