ToolBirch

Ratio Calculator

Scale ratios: A:B with a new value for either side.Math & Statistics

Ratio Calculator

Scale one side of a ratio: enter A:B and a new value for either side to get the matching value.

About this tool

Give A:B and one new value — the matching value follows. The simplified form (via GCD) and the decimal ratio are shown when no scaling value is entered.

How to use the Ratio Calculator tool

  1. Enter A and B. Any positive numbers, same units.
  2. Enter the new A or new B. Whichever side you actually know.
  3. Read the match. Computed to four decimals.

Supported formats

Input

  • Plain text or file input

Output

  • Converted or analysed output

Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.

Frequently asked questions

How is scaling computed?

Cross-multiplication: newB equals newA times B divided by A.

What does simplified mean?

Both sides divided by their GCD: 1920:1080 becomes 16:9.

Do units matter?

No, as long as both sides share them.

Privacy

Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.

No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.

Known limitations

  • Zero or negative values are rejected; ratios need positive magnitudes.

Related tools

Other free tools from the same collection.

Average CalculatorMean, median, sum and range for a list of numbers.Median CalculatorThe middle value of an ordered list, outliers be damned.Standard Deviation CalculatorPopulation and sample standard deviation, clearly labelled.Fraction CalculatorExact fraction arithmetic with simplified results.