Methodology
How Answerivo calculators are built
The formula is on the page
Every calculator shows the exact steps it runs, in the order it runs them, under “How this calculation works”. If a figure looks wrong you can follow the arithmetic rather than trust a black box.
Worked examples are checked against the code
Each page carries a worked example you can load into the form with one click. Those example inputs and the values they produce are covered by an automated test suite that runs against the same functions the page uses, so the walkthrough cannot drift away from the math.
Your numbers stay in your browser
Calculations run in the page itself. Nothing you type into a calculator is sent to a server, saved to an account, or stored by us — there is no account to create. Anonymous usage events (such as “a calculation ran”) are counted without inputs or results. The one exception is Ask Answerivo: a question you type there is sent to an AI service to pick a calculator and is not saved.
Assumptions are stated, not hidden
Where a result depends on a choice — a tax basis, an overtime threshold, whether a discount is applied before tax — the page says which choice it makes. Rules that vary by country, state, or employer are inputs you control, not values we guess.
How formulas are tested
Each calculator's math lives in one function that both the full page and the embeddable version call, so the two cannot disagree. An automated test suite checks worked examples, edge cases (zero values, very short or long terms, invalid inputs) and hand-calculated results before any change is released. Results are informational estimates from the formula shown — not quotes, approvals or professional advice.
How formulas are chosen
We use the standard textbook form of each calculation — the amortization formula for loan payments, percent change measured from the starting value, margin measured on price and markup on cost — and say so on the page. Where people commonly mean different things by the same word, the calculator either offers both modes or names the one it uses.
Defaults and assumptions
Every input starts with an example value so the page shows a working answer straight away. Those defaults are illustrations, not recommendations or averages for your area; replace them with your own figures. Anything that varies by lender, employer, state or country — tax rates, overtime multipliers, debt-to-income limits — is an input you can change.
Rounding
Calculations run at full precision and are rounded only for display: money to the cent, percentages to two decimal places, and counts to whole numbers. Because of this, adding up rounded figures on the page can differ from a total by a cent. Per-unit costs that would round to zero show up to four decimal places.
What we do not do
Answerivo does not give accounting, legal, tax, or investment advice, and it does not decide what the rules are where you live. A payment estimate is not a loan offer, an overtime split is not a legal determination, and a rental projection is not underwriting. Anything with real money attached should be confirmed with the lender, payroll provider, or professional who is responsible for it. Our disclaimer sets this out in full.
Updates and corrections
Spotted something that looks off? Tell us and we will check it.
A useful report includes the page, the inputs you entered and the result you expected. When an error is confirmed we fix the formula and add a test for that case so it cannot come back; when the page was right but unclear, we improve the explanation.