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Reduce any ratio to its simplest form, like 12:18 → 2:3.
Simplify ratios to their lowest terms in one step — enter 12:18 and get 2:3 instantly. Useful for recipes, scale models, screen aspect ratios, and mixing solutions. The decimal value of the ratio is shown alongside.
A ratio compares two or more quantities in the same units — 18 boys to 24 girls in a class, or a recipe's 2:3:1 mix of flour, sugar, and butter. Simplifying a ratio means dividing every term by their greatest common divisor so the relationship is expressed in the smallest whole numbers, exactly like reducing a fraction. 18:24 simplifies to 3:4 because both divide evenly by 6, and the simplified form is easier to reason about: for every 3 of one thing there are 4 of the other. Ratios with three or more terms simplify the same way, using the GCD of all terms at once.
Ratios also scale, which is their real power. Once simplified, you can multiply every term by the same number to size a recipe up or down without changing its character: 3:4 scaled by 10 becomes 30:40. Map scales, model building, and currency-free price comparisons all run on this principle. The pitfall is mixing up ratios with fractions of a total — a 3:4 ratio means 3 parts out of 7 total, so the first quantity is 3/7 of the whole, not 3/4. And ratios only compare like with like: 3 apples to 4 oranges is fine as a count ratio, but 3 meters to 4 seconds is not a meaningful ratio without a shared context like speed. A practical cousin is the unit rate: divide one term by the other to get 'per one' pricing. A 3:4 ratio of concentrate to water at $12 for 3 liters of concentrate means $4 per liter of concentrate, or $12/7 = $1.71 per liter of mixed drink. Grocery 'unit price' labels do exactly this so you can compare a 12-ounce box with an 18-ounce box honestly. Ratios tell you the shape of a mixture; unit rates tell you its price — simplify first, then divide.
Both sides are divided by their greatest common divisor (the Euclidean algorithm), so 12:18 becomes 2:3. The decimal value is simply the first number divided by the second.
The greatest common divisor of 18 and 24 is 6. Divide both terms: 18 / 6 = 3, 24 / 6 = 4. Simplified ratio: 3:4. Verify the relationship is preserved: 3/4 = 0.75 and 18/24 = 0.75 — identical. As shares of a total: the parts are 3/7 and 4/7 of the whole, so in a class of 35 with this ratio there would be 15 of the first group and 20 of the second (35 x 3/7 = 15, 35 x 4/7 = 20).
The greatest common divisor of all three terms is 50. Divide each: 150/50 = 3, 100/50 = 2, 50/50 = 1. Simplified ratio: 3:2:1 — a 6-part total, so the shares are 3/6 = 1/2, 2/6 = 1/3, and 1/6 of the whole. Scaling example: a paint mix of 3:2:1 needing 12 liters total uses 6, 4, and 2 liters (12 x 3/6 = 6, 12 x 2/6 = 4, 12 x 1/6 = 2).
Type 12:18 — the calculator divides both sides by their greatest common divisor (6) and returns 2:3.
You can type 12:18, 12,18, or 12 18 — all are understood. Decimals work too, e.g. 2.5:5 simplifies to 1:2.
It shows the ratio as a single number (12:18 = 0.6667), which is handy when you need to compare ratios or use one in further calculations.