All categories

Run the numbers on mortgages, loans, credit cards, investments, and retirement — with transparent formulas and editable assumptions.

Percentages, fractions, ratios, geometry, and the little calculations that come up all the time — with formulas you can reuse anywhere.

Means, medians, standard deviations, confidence intervals, and sample size planning — with formulas and worked examples for each tool.

BMI, body fat, BMR, and other health screening tools — clearly labelled as informational rather than diagnostic, with citations for each for...

Pace calculators, one-rep max estimators, and training volume tools that match how coaches actually program.

Solve the common physics textbook calculations — velocity, acceleration, force, and energy — with units correctly tracked end to end.

Solution concentration, dilution, and reaction math — with careful unit handling and explanations of the underlying relationships.

Paint coverage, tile counts, concrete volumes, and roofing math — with sensible defaults for home projects and trade work.

Unit conversions with exact definitions where available and clearly documented constants where approximations are unavoidable.

The calculators that come up in day-to-day life — tip splitting, cooking conversions, fuel costs, and trip planning.

Running, cycling, swimming, and gym math — from race pace and splits to power-to-weight and training-load calculations.

Recipe scaling, cups-to-grams conversions, portion planning for parties, and ingredient substitutions — with the formulas visible.

Quick reference calculators for the life sciences — Punnett squares, lung capacity, protein requirements, population growth, and more.

Estimate the footprint of travel, food, and energy choices — with transparent emission factors you can inspect and edit.

Time and date math, randomness, passwords, games, and miscellaneous calculators that are genuinely useful but don't fit a single category.