Ratio Calculator
Reduce a:b and scale either side. Click any i for detail.
Ratio
A
i
A
First term. |
|
|---|---|
B
i
B
Second term. |
|
Scale so A =
i
Scale A
Optional — leave blank to skip. |
|
Scale so B =
i
Scale B
Optional — leave blank to skip. |
How to use this calculator
- Enter the two terms A and B.
- Read the reduced ratio and decimal A/B.
- Optional: scale so A or B equals a target value.
- Use the scaled row when a recipe or mix needs a fixed part.
Results explained
A ratio compares two quantities. Reducing divides both by their GCD. Scaling multiplies both so one side hits your target without changing the relationship.
Quick reference: ratio math
8:12 reduces to 2:3 because gcd(8,12) = 4.
| Item | Detail |
|---|---|
| Reduce | divide A and B by gcd(|A|,|B|) |
| As fraction | A/B in decimal form |
| Scale A | multiply both by target/A |
| Part of whole | A/(A+B) is A's share of the total |
Gear ratios and pixel aspect ratios use different pages when units matter.
How the estimate is built
reduced A:B = A/g : B/g; scale factor k = target/A or target/B.
Example scenario
8:12 → 2:3; decimal 0.667.
FAQ
How do I get a percentage from a ratio?
A/(A+B) × 100 is A's percent of the combined total.
Can ratios be negative?
Math allows it; most real mixes use positive terms.
Is 16:9 the same as this page?
Same idea, but the aspect ratio page handles pixel width and height.