Math calculators

The everyday math questions, answered live.

Percentage calculator % of, what %, and % change Average calculator Mean, median, min/max of any list Ratio calculator Simplify and scale — 1920:1080 → 16:9 Fraction ↔ decimal Both directions, with the chart Rule of three A:B = C:X — proportions solved Weighted average Grades and scores: Σ(v×w) ÷ Σw, live Grade calculator Current grade + what you need on the final GPA calculator 4.0 scale × credit hours, live Standard deviation Sample & population, with steps Square footage Feet & inches in, sq ft + m² out
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Every math calculator here follows the same rules: results update live as you type, the formula is shown with a worked example, and the math runs entirely in your browser — nothing you enter is uploaded anywhere. More math calculators are added regularly; each one is unit-tested against published reference values before it ships.