Principles
- Useful first. A page is published only if it helps someone do something the calculator alone would not, such as understand a formula, avoid a common mistake or see a worked example.
- One page per purpose. We do not create near-duplicate pages to catch search variations.
- Plain language. American English, short sentences, defined terms.
- Honest limits. Each calculator states its assumptions and what it does not do.
How a calculator is built and checked
- The formula is written down from an authoritative source, such as a Department of Labor fact sheet or a standard textbook definition.
- The calculation code is separated from the page and tested against answers worked out by hand, covering normal values, zero, negatives, decimals, very large numbers, blank and invalid input, leap years, daylight saving time, overnight shifts and rounding edges.
- The page is read in a browser at phone, tablet and desktop widths, with a keyboard and with automated accessibility checks.
- The worked example on the page is taken from the same verified numbers the tests use.
A calculator that fails any of these steps is not published. See calculation methodology for rounding and date rules.
Sources
Where a rule comes from law or government guidance, the page cites it: for example U.S. Department of Labor fact sheets, the Code of Federal Regulations and the Office of Personnel Management holiday schedule. We prefer primary sources. We do not copy competitor text, and we write our own examples.
Use of AI tools
Jodbrain Studio uses AI tools to help draft text and write code. AI output is never published on trust: formulas are verified by automated tests against independent hand-worked answers, and claims about laws and rules are checked against the cited sources before publication.
Updates and corrections
Pages show when they were last reviewed. We review calculators when rules change, such as holiday schedules or federal salary thresholds, and when readers report a problem. Confirmed errors are corrected promptly. For a material correction we update the page and its review date. To report an error, use the contact page.
Independence
SumPanda does not accept payment to change a result, rank a product or place a link. If advertising is added in the future, ads will be clearly separated from calculators and results, and this page and the privacy policy will be updated first.