Ratio Calculator
Simplify ratios, solve for a missing term, and scale a ratio to a total.
Formula
a : b = c : d → d = bc / a
Tips
- A ratio compares parts to each other; a fraction compares a part to the whole. In 3:4, A is 3/7 of the total, not 3/4.
- Scaling a recipe or a mix is a proportion problem: keep A:B fixed and solve for the new quantity.
- Aspect ratios are just ratios in their simplest form — 1920:1080 reduces to 16:9.
Frequently asked questions
What is the difference between a ratio and a rate?
A ratio compares two quantities of the same kind and has no units. A rate compares different kinds — miles per hour, cost per unit — and carries units.