Ratio to percentage calculator
Convert between product:water ratios, final-mixture percentages and “1 in N” total parts.
How to use this calculator
- Choose the notation used in your instructions.
- Enter the parts or percentage using one measurement basis for both ingredients.
- Convert and compare all three expressions. Check the worked example if the ratio convention is unclear.
Worked example
1:4 product:water means 1 product part plus 4 water parts. Product is 1 ÷ (1 + 4) × 100 = 20% of the final mixture, also written 1 in 5 total parts. By comparison, 1 in 4 means 1 product part within 4 total parts: 25% product, equivalent to 1:3 product:water.
Questions about this calculation
How do I convert an additive ratio to a percentage?
Divide the product parts by the sum of product and water parts, then multiply by 100. For 1:9 product:water, the product percentage is 1 ÷ 10 × 100 = 10%. This is a percentage of the final mixture.
Is 1:10 the same as 1 in 10?
When 1:10 means product:water, it has 11 total parts and about 9.09% product. 1 in 10 includes the product in 10 total parts, so it is 10% product and equivalent to 1:9 product:water. Confirm which convention your instructions use.
What do 0% and 100% mean?
0% is water only, with no product; no finite 1 in N expression describes zero product. 100% is pure product with no added water, equivalent to 1:0 product:water or 1 in 1 total part.
Does this calculate active ingredient concentration?
It calculates the share of product as supplied in the mixture. If the product is itself a concentrate, its active ingredient concentration is a separate input and calculation. Do not treat the product percentage as the active ingredient percentage.
Can I mix weight parts with volume parts?
No. Both parts must use the same basis. Use compatible mass units for a weight ratio or compatible volume units for a volume ratio; converting between the two requires the relevant densities.