Methodology & corrections policy

How each calculator is built

• One definition per calculator. Each of our 152+ tools is a single source file that defines its inputs, validation and formula. The same code produces the page you see, runs in your browser, and answers our API – so every channel gives the same result.
• Published formulas and official rules. Finance tools use standard formulas (for example the amortization formula used by lenders). Tax, payroll, employment-law and benefit tools use the rules published by the relevant authority – such as the IRS, SSA, HMRC/GOV.UK, the Canada Revenue Agency and provincial governments, and GCC labour laws and agencies. Each page's guide states the jurisdiction, the tax year or rule version it applies, and its sources.
• Stated assumptions. Where a tool simplifies (for example a flat state tax rate, or ignoring credits), the page says so. Results are estimates for general information, not financial, tax, legal or medical advice.

How we test

• Every calculator has automated tests with hand-checked reference cases – for example IRS bracket examples, published government worked examples (such as the City of Montréal's welcome-tax example), and textbook values for statistics functions. The test suite runs before every deployment; a failing test blocks the release.
• Tests also check that each page's “quick answer” matches what the calculator actually computes, that default results contain no invalid values, and that invalid inputs produce clear error messages.
• Calculators and their explanations are developed with the help of AI coding tools. Figures that change over time (tax brackets, limits, fees) are checked against official sources; where only secondary sources could be found, we note it and re-check when the authority publishes an update.

Keeping rules current

Tax years, contribution limits and fees change, usually once a year. We update affected calculators when new figures are published and show the rule year on the page. The “Updated” date on each calculator is the date its code or content last changed – not simply the date the site was rebuilt.

Corrections policy

If you think a result, rule or explanation is wrong, please email[email protected] with the calculator, your inputs and the source you're comparing against. We review every report. Confirmed errors are fixed, a test case is added so the error can't return, and the page's updated date changes with the fix. Significant corrections to tax or legal rules are noted in that calculator's guide.

Independence

CalcBright is free and supported by advertising. Ads never change calculator results, and we don't accept payment to recommend lenders, advisers or products.