Proportion Calculator
Solve a missing value in A:B = C:D or formula. Shows the completed proportion, scale factor, and check.
Solve a direct proportion
English proportion calculator intent is usually a missing-value solver: enter three values in A:B = C:D, leave one blank, and get the missing term with a cross-multiplication check.
The calculator solves one missing value in this direct proportion.
Cross products match when the two ratios are equivalent.
What this calculator does not solve
- It requires exactly one blank field.
- It solves direct proportions, not inverse variation word problems.
- B and D cannot be zero because they are denominators in.
Frequently Asked Questions
Sources and References
Calculations are based on the listed reference sources. Links open in a new tab.
Related Tools
Simplify ratios, convert ratio parts to percentages, compare decimal form, and split a total by a two-part or multi-part ratio.
Calculate mean, median, mode, range, sum, count, variance, standard deviation, geometric mean, and harmonic mean for a data set.
Calculate percent of a number, what percent one number is of another, reverse percentage, percentage change, and add or subtract a percentage.
Calculate a mod b and compare JavaScript-style remainder with Python-style modulo for positive, negative, integer, and decimal inputs.
Round numbers to decimal places, whole numbers, or a nearest multiple. Compare half-away, half-even, ceiling, floor, and truncation results.