Disclaimer

The calculators on this site are educational tools. They apply published formulas to the numbers you enter. They do not know your circumstances, and no result here is a substitute for advice from someone qualified to give it.

Financial calculators

Loan, investment, retirement and tax calculators model a formula, not a product. A real loan carries processing fees, insurance requirements, prepayment penalties and terms that vary by lender and jurisdiction — none of which this site can know. Investment projections assume a fixed return that markets do not deliver; they describe a scenario, not an expectation.

Nothing on this site is financial, investment, tax or legal advice, and we are not licensed to give it. Speak to a regulated adviser before committing to a loan, an investment or a retirement plan.

Health and fitness calculators

BMI, body fat, calorie, pregnancy and heart-rate tools apply formulas derived from population averages. They can be substantially wrong for any given individual — an athlete's BMI, a tape-measure body fat estimate, a due date calculated from an irregular cycle. They cannot detect a condition, and a normal-looking result is not a clean bill of health.

Nothing here is medical advice, diagnosis or treatment. Consult a qualified clinician before changing your diet, exercise or medication, and seek professional care for any health concern. If you may be experiencing a medical emergency, contact emergency services rather than a website.

Construction and engineering estimates

Material quantities for paint, tiles, concrete and brickwork are indicative and use nominal mixes and standard component sizes. Real sites differ in ways these figures cannot capture. Structural work must follow a qualified engineer's specification, not a general-purpose calculator.

Statistics calculators

Confidence intervals, p-values, sample sizes and correlations are arithmetic applied to the numbers you supply. They cannot tell you whether your data was collected well, whether your sample was representative, or whether the assumptions behind a test are met — and those questions usually matter more than the figure. A margin of error describes sampling variation only; it makes no allowance for non-response or a biased sampling frame, which are frequently the larger problem.

Statistical significance is not practical importance, and a p-value is not the probability that a finding is real. Do not treat any result here as a substitute for a statistician on work that will be published, submitted or relied upon.

Physics and engineering calculators

Every physics tool here implements an idealisation, and each page states which one. Kinetic energy ignores rotation, projectile figures ignore air resistance, the ideal gas law fails at high pressure, and Ohm's law assumes a component whose resistance does not change with voltage or temperature. Results are correct for the model and can be substantially wrong for the real object.

These are teaching and estimating tools. They are not design tools, and nothing here should be used to size a component, specify a circuit or verify a safety margin.

Accuracy and errors

The calculation engines are covered by automated tests and verified against published formulas and reference values. Many of them are shared with our Android app, so those results agree across both; the physics, statistics and newer conversion tools are web-only and are checked against published tables instead. Despite that, errors are possible, and we make no warranty that every result is correct. Verify anything consequential independently, and please report anything that looks wrong — see the methodology page for how corrections are handled.

External links and advertising

Advertisements and external links are not endorsements. We do not control third-party content and accept no responsibility for products or services advertised or linked here.