Math calculators

Percent and Ratio Calculators

5 tools

Percentage, percent change, percent error, ratios, and proportions. Tools may appear in more than one topic.

Popular in Percent, Ratio & Proportion

Featured tools from the Family registry.

Percentage Calculator Calculate percentages, percentage of a number, and “what percent is X of Y” with clear arithmetic steps. Runs locally in your browser. Try it free.
Ratio Calculator Simplify, scale, split and compare exact ratios, solve proportions, and convert parts to percentages. See formulas, input limits, worked steps and exports.

Every live calculator in this family. URLs stay /calc/math/…

Percent Error Calculator Calculate absolute or signed percent error, solve for observed or accepted values, and inspect every inverse branch, numerical limit, formula and export.
Percentage Calculator Calculate percentages, percentage of a number, and “what percent is X of Y” with clear arithmetic steps. Runs locally in your browser. Try it free.
Percentage Change Calculator Calculate percentage increase or decrease and reverse-solve initial or final values. See complete signed solutions, formulas, and numerical limits.
Proportion Calculator Solve a proportion for one missing term using exact rational arithmetic. Enter integers, decimals or fractions; check nonzero denominators and worked steps.
Ratio Calculator Simplify, scale, split and compare exact ratios, solve proportions, and convert parts to percentages. See formulas, input limits, worked steps and exports.