Simplify a ratio
e.g. 8 : 12 reduces to 2 : 3
Scale a ratio
e.g. 2 : 3 = 6 : ? (resizing a recipe or photo)
Last updated 23 August 2026
Simplify vs scale
Simplifying takes a ratio like 8:12 and reduces it to the smallest whole numbers that describe the same relationship — 2:3. Divide both sides by their greatest common divisor and that's the answer.
Scaling answers a different question: if 2:3 stays proportional and the first number becomes 6, what does the second number become? Multiply the known ratio through: 6 ÷ 2 × 3 = 9, so 2:3 scales to 6:9. This is exactly the maths behind resizing a recipe, a photo, or a scale model while keeping the proportions correct.
Common questions
How do you simplify a ratio?
Divide both numbers by their greatest common divisor. 8:12 and 2:3 describe the same relationship, but 2:3 is the simplest form — the calculator finds that divisor automatically.
How does scaling a ratio work?
If A is to B as C is to an unknown, the unknown equals B × C ÷ A. This is the same maths as resizing a recipe or a photo while keeping the proportions identical.
Can a ratio have more than two numbers?
Yes, ratios like 2:3:5 are common, but this calculator handles the two-number case, which covers the large majority of everyday uses like mixing, scaling and resizing.