Ratio Calculator
Simplify a ratio or solve for a missing value in a proportion.
This tool runs entirely in your browser. Your files are never uploaded to a server.
Simplify a:b, and solve a:b = c:d — leave one of c/d empty to solve for it.
1:2
Simplified ratio
20
Solved for d
Enter finite a and b values to display a simplified a:b and solve a:b = c:d. When d is blank the tool calculates d = b × c / a; once d has a value it calculates c = a × d / b. Simplification finds a greatest common divisor from the rounded absolute a and b values, then divides the original values by it, so whole-number ratios are the reliable use case and decimal output may not be mathematically minimal. b cannot be zero; a = 0 can make the solved value non-finite. Results are local and non-integers are shown to two decimals.
Frequently Asked Questions
- How is a ratio simplified?
- Both numbers are divided by their greatest common divisor (GCD), reducing the ratio to its smallest whole-number form.
- How do I solve for a missing value?
- Fill in a, b and c, and leave d blank (or vice versa) — the calculator solves the proportion a:b = c:d for the missing value.
- Can ratios include decimals?
- Yes, decimal values are accepted, though simplification works best with whole numbers.