Ratio Calculator

Simplify ratios and calculate proportional values.

Simplify a Ratio

Solve Proportion (A:B = C:?)

How to Do It Manually

Ratios compare quantities. To simplify a ratio, divide both values by their GCD. To solve a proportion, cross-multiply.

If a:b = c:d then a × d = b × c (cross-multiply)
  1. Write the two ratios as fractions: a/b = c/d.
  2. Cross-multiply: a × d = b × c.
  3. Solve for the unknown variable by dividing both sides.

Frequently Asked Questions

How do I simplify a ratio?

Find the GCD of the two numbers and divide both by it. Example: 12:8 → GCD 4 → 3:2.

What is a proportion?

A proportion states that two ratios are equal (a:b = c:d). Use cross-multiplication to solve for an unknown.