=Calculate
Math & numbers · Proportion

Ratio
calculator

Simplify 48:36 to lowest terms, or solve the missing piece of A:B = C:x — the proportion math behind recipes, maps, screens and scale models, done instantly.

Simplify & solveShows the workNo sign-up
lowest terms
:
As a decimalA ÷ B
As "1 : n"normalized to one

Ratios: division wearing a colon

A ratio compares two quantities by division. Simplifying means dividing both sides by their greatest common factor — 48:36 shares a GCF of 12, so it reduces to 4:3, the shape of a classic screen.

Solving a proportion
A:B = C:x → x = C × B ÷ A
3 : 4 = 15 : x
x = 15 × 4 ÷ 3 = 20 — cross-multiplication in one line.

Where you meet them

Recipes scale by ratio (double every ingredient, the ratios hold); maps state 1:50,000; screens are 16:9; scale models 1:24; coffee brews at 1:16. The "1 : n" form shown above is the most comparable version of any ratio — it's how map scales and mix ratios are quoted.

Ratios and fractions are the same idea in different clothes: 4:3 is the fraction 4/3. The fraction calculator does the four operations on them, and GCF & LCM exposes the machinery this page uses to simplify.

Common questions

Ratio FAQ

Divide both sides by their greatest common factor. 48:36 has a GCF of 12, so it simplifies to 4:3.

Cross-multiply: x = C × B ÷ A. For 3:4 = 15:x, x = 15×4÷3 = 20.

The left side normalized to one — the standard form for map scales (1:50,000), mix ratios and comparisons. 4:3 becomes 1:0.75.

Yes — 2.5:1.5 is valid. This tool simplifies whole numbers exactly via GCF, and normalizes decimal ratios to the 1:n form instead.