Proportion calculator
Enter your values to see the result, check the formula and copy your calculation.
Enter your values, then calculate.
Your calculation stays in your browser.
The formula, explained
a*c/ba : Reference amountb : Reference quantityc : Required quantityAn example to check
Using the starting values below, the calculation gives:
How to use this tool
Check the required inputs: reference amount, reference quantity, required quantity.
Choose the units and options that match your task. Calculate, check the result and use Copy or Print to keep a record. Rounding applies to the display; keep more precision in intermediate steps.
Can I use a decimal comma?
Yes. Numeric fields accept 12.5 or 12,5 and spaces for thousands, such as 1 234.50. Do not mix a point and comma in one number.
Where are my inputs processed?
Calculations run in your browser. Form values are not sent to Analytics. Copying, printing, sharing or opening an external service is your choice.
Method and interface checked on 2026-09-12 · Report an error