Simplify a ratio, scale it to find a missing number, or split a total into shares in a given ratio. It handles two or three parts.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Ratio calculator works
There are three modes.
- Simplify a ratio: enter two whole numbers above zero. The tool divides both by their greatest common divisor, so 24:36 becomes 2:3. It also shows the share as a fraction of the total and the decimal ratio A to B.
- Find a missing number: enter A and B, then the new value of A. The scale factor is new A divided by A, and B becomes B × that factor. This keeps the ratio the same.
- Share an amount: enter two or three parts (leave the third at 0 for a two-part ratio) and a total. Add the parts together, then each part’s share is the total × part ÷ sum of the parts. The results show each share and its percentage.
Simplifying needs whole numbers. The other modes accept decimals. All parts must be positive, and results are rounded for display, so shares may differ by a penny when a total does not divide neatly.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| What you want to do | Simplify a ratio |
| First number (A) | 24 |
| Second number (B) | 36 |
Simplest ratio: 2 : 3
| Divided by | 12 |
|---|---|
| As a fraction of the total | 2/5 |
| Decimal ratio, A to B | 0.666667 |
Tips and common mistakes
Make sure both sides use the same units before you start, such as grams with grams. When sharing money, the shares are rounded to two decimal places, so check they add up to the total and adjust the last share if they do not.
For scaling a recipe or a plan, the missing-number mode saves repeating the sum. To turn the shares into percentages, they are already listed, or you can use Percentage of a number. For fractions, see Fraction calculator.
Frequently asked questions
How do I simplify a ratio?
Divide every number in the ratio by their greatest common divisor. For 24:36 that is 12, giving 2:3.
How do I share an amount in a ratio?
Add up the parts, divide the total by that sum, then multiply by each part. The calculator shows each share and its percentage.
Can it handle a ratio with three parts?
Yes, in the share mode. Enter a third number, or leave it at 0 for a two-part ratio.