Ratio Calculator
Two or more parts, separated by colons.
Optional.
2 : 3
- 40%
- Part 1 share
- 60%
- Part 2 share
The ratio calculator simplifies a ratio to its lowest whole-number terms, shows what share each part represents as a percentage, and scales the whole ratio so the first part hits a target you set. It handles any number of parts, not just two. Useful for recipes and for splitting costs three or more ways.
How it works
Simplification divides every part by the greatest common divisor of all of them, which is why 24:36 becomes 2:3 and 2:3:5 stays as it is.
- Each part’s share is that part divided by the total of all parts, as a percentage.
- Scaling multiplies every part by the same factor, so the relationship is preserved.
- Non-integer parts are left as entered, since there is no whole-number simplification for them.
Examples
Simplifying a two-part ratio
Ratio
24:36
Result
2 : 3 · shares 40% and 60%
Both parts divide by 12. The percentages come from 24/60 and 36/60.
A three-way split
Ratio
2:3:5
Result
2 : 3 : 5 · shares 20%, 30%, 50%
Already in lowest terms, since the three parts share no common factor. The percentages are what matter when splitting a bill or a profit share.
Scaling a recipe
Ratio
2:3
Scale first part to
500
Result
500 : 750
Scaling by 250 preserves the relationship. This is the calculation behind adjusting a recipe to the flour you actually have.
Frequently asked questions
How does simplifying a ratio differ from simplifying a fraction?
The arithmetic is identical, divide by the greatest common divisor, but a ratio can have three or more parts, where a fraction has exactly two. 24:36 and 24/36 both reduce by 12; 2:3:5 has no fraction equivalent.
What is the difference between a ratio and a percentage?
A ratio compares parts to each other; a percentage compares a part to the whole. In 2:3, the first part is two thirds of the second but 40 percent of the total. Confusing the two is the usual source of error in mixing and dilution.
Can I use decimals in a ratio?
Yes, but they will not simplify, because there is no whole-number common divisor. The percentages and the scaling still work. Multiply through by a power of ten first if you want a whole-number form.
How is this different from the aspect ratio calculator?
This one works with any number of parts and answers share and scaling questions. The aspect ratio calculator is specifically about pixel dimensions, and adds the things that matter there, megapixels, and calculating the matching height for a new width.