Frequently asked questions

A free library of hundreds of calculators for finance, health, math, construction, conversion and everyday questions. Every tool shows the formula it uses, defines its variables, and works through an example.

No. There are no accounts, no sign-ups and no paywalls. Every calculator is available immediately.

Yes. The site is funded by advertising, which is why you occasionally see ad units alongside content. Advertisers have no influence on our formulas or explanations.

You may use results in your own work, but they remain estimates. For contractual, regulatory or clinical purposes, verify them with a qualified professional.

Please do. Send the request through the contact page describing the calculation and, if possible, the source formula you expect us to use.

Implementations reproduce their source formulas to the precision the source provides, and are tested against published reference values. Accuracy of the result in your situation depends on whether the model's assumptions apply to you.

Government and regulatory publications, standards bodies, peer-reviewed literature and established reference texts. The calculation methodology page explains our sourcing hierarchy.

Usually because of different assumptions: compounding frequency, rounding, day-count conventions, whether fees or taxes are included, or a different underlying formula. Our pages state which assumptions we use.

Intermediate values are kept at full precision and only the displayed result is rounded, using the convention normal for that domain — currency to cents, materials rounded up to whole units.

Use the contact page with the calculator URL and the exact inputs. We reproduce the issue, fix confirmed errors promptly, and note material corrections on the page.

Not unless the tool exposes them as inputs. The base payment covers principal and interest only, which is the figure lenders quote as P&I.

Rates are nominal annual rates unless a page states otherwise, compounded at the frequency shown on the tool.

Treat them as planning estimates. Lenders apply their own fees, criteria and rounding, so their official figures take precedence.

Tax tools state the jurisdiction and tax year they model. Rules change frequently — always confirm against your tax authority before filing.

Only where inflation is an explicit input. We do not forecast market or inflation rates on your behalf.

Published clinical formulas — for example Mifflin–St Jeor for basal metabolic rate and the standard weight/height² definition of BMI. Each page names its formula.

No. BMI does not distinguish muscle from fat, and it is a poor indicator for athletes, pregnant people, children and some ethnic groups. It is a population screening measure, not a diagnosis.

No. Health calculators are educational. They cannot diagnose, treat or replace advice from a qualified clinician.

Activity multipliers and the underlying BMR equation differ. We state which equation and multipliers a tool uses so you can compare like with like.

Margin expresses profit as a percentage of the selling price; markup expresses it as a percentage of cost. The same absolute profit produces two different percentages, which is why we provide both tools.

Only when tax is an explicit input. Sales tax, VAT and GST vary by jurisdiction and are excluded from base pricing calculations by default.

They are useful for planning and sanity checks, but reporting figures should come from your accounting system and be reviewed by your accountant.

No. Calculations run entirely in your browser and inputs are never transmitted to our servers.

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Use the "Cookie preferences" link in the footer, or the button on the cookie policy page, at any time.

No. We do not sell or share personal data for cross-context behavioural advertising beyond the standard AdSense mechanisms you consent to.

Confirm every required field has a value and that JavaScript is enabled. Ad blockers occasionally block scripts the page needs; try disabling one temporarily.

Pages you have already loaded may work offline in some browsers, but the site is not designed as an offline application.

Yes. Calculator pages include print, copy, share and PDF export actions that keep the formula and inputs alongside the result.

The current and previous major versions of Chrome, Edge, Firefox and Safari on desktop and mobile.

Not yet — mobile apps are in development. The site is fully responsive in the meantime.