Ratio scaler
Enter the original ratio, pick the term whose new value you know, and the tool works out the other terms and the scale factor.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter first term, second term, third term (optional), known term and its new value.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Scale factor = new value ÷ chosen term; each new term = original term × factor
Example
Inputs: First term = 2, Second term = 3, Third term (optional) = 5, Known term = First, Its new value = 10. Result: Scaled ratio: 10:15:25; Scale factor: 5; New term 1: 10.
Limits and caveats
- The ratio text is rounded to at most 6 decimal places.
- Takes up to 3 positive terms.
Questions about this tool
A mix is 2:3:5 and I want 10 of the first part. How much of the rest?
The scale factor is 10 ÷ 2 = 5, so the amounts become 10, 15 and 25.
Can I scale a ratio down?
Yes. If the new value is smaller than the original term, the factor is below 1 and every term shrinks.
Does scaling change the ratio itself?
No. 10:15:25 simplifies back to exactly 2:3:5.