Where our numbers come from, how we check them, and what we do when we get one wrong.
A time or pay calculator is only worth using if the math behind it is right. This page sets out how we build the tools on TimeCardTools, the published rules and sources we check our figures against, how often we review them, and the policies that keep advertising separate from the results you see.
None of the methods here are proprietary. Hours worked is end time minus start time, with unpaid breaks removed. Decimal hours is minutes divided by 60, which is why 30 minutes is 0.50 and 45 minutes is 0.75. Overnight shifts add 24 hours, or 1,440 minutes, when the clock-out falls before the clock-in. Military time subtracts 12 from afternoon hours, and time zone conversion works through Coordinated Universal Time so daylight saving is handled by the date. We use the same arithmetic a payroll clerk would, and we show the worked example on each page so you can follow it by hand.
Where a number reflects a legal rule rather than plain arithmetic, we check it against a primary source and cite it on the page. The ones we lean on most:
When a figure is a genuine range or a custom rather than a fixed rule, like restaurant tipping or the number of business days in a month, we give the range and say so rather than pretending there is one exact number.
Our tools size a number for your own planning. They are not a substitute for your employer's payroll, your state labor agency, or a lawyer. Real pay depends on details these calculators do not know: state law that adds daily overtime, your employer's rounding and break policies, nondiscretionary bonuses that raise the regular rate, and your own filing status and deductions, which is why every result is gross pay before taxes. For anything that affects what actually lands in your check, confirm the final number with your employer or payroll department.
Each tool and guide is reviewed when we publish it and again whenever a cited rule changes, a reader flags a problem, or a federal figure is revised. Year-specific figures, such as the federal minimum wage or holiday dates, state the year and link the source. The person who signs off on every formula and every cited figure before it ships is named, along with what they specifically check, on the authors page.
If a calculator returns a wrong result, or a page states a figure you can show is off, email us and we will check it against the source and fix it. We would rather correct a number quickly than defend a bad one. There is no form to fill out and no account to create. The fastest way to reach us is the contact page.
TimeCardTools is free to use and pays for itself through display advertising and a small number of affiliate links to related payroll and HR services. If you click an affiliate link and sign up or make a purchase, we may earn a commission at no additional cost to you. Advertising and affiliate revenue never influence the formulas, the rules, or the recommendations in our tools and guides. Ads are labeled, and the affiliate disclosure appears at the foot of every page.
Want to know who writes and checks this material day to day? See the authors page for the two people behind everything published here and exactly what each of them checks before a page goes live.