Resin Mix Ratio Calculator
Two-part resins cure correctly only at the mix ratio the manufacturer specifies. Enter the total batch you want, then the ratio of resin (part A) to hardener (part B) from your product's data sheet, and this calculator gives the exact amount of each part to measure, in the same units you entered.
Resin mix ratio formula
Total parts = A + B
Resin = total batch * A / total parts
Hardener = total batch * B / total parts
Hardener share = B / total parts * 100
Keep the batch units and the ratio on the same basis: a by-weight ratio with grams, or a by-volume ratio with millilitres.
Worked example: a 2:1 resin
For a 200 gram batch at a 2:1 ratio, total parts = 3. Resin = 200 times 2 / 3 = 133.33 g. Hardener = 200 times 1 / 3 = 66.67 g. The hardener share is 1 / 3 = 33.33 percent of the batch.
Resin mix ratio: frequently asked questions
How do I split a resin batch by its mix ratio?
A mix ratio of A to B means for every A parts of resin you add B parts of hardener. The total is A plus B parts. Resin = total times A divided by (A plus B); hardener = total times B divided by (A plus B).
Should I measure by volume or by weight?
Follow the ratio your product's technical data sheet specifies, and use the matching method. A 1:1 by volume ratio is not the same as 1:1 by weight unless the two parts have equal density. This calculator works for either as long as your inputs and ratio use the same basis.
Why is the resin mix ratio so important?
Epoxy and other two-part resins cure by a chemical reaction between the parts. An off-ratio mix can stay tacky, cure soft or never fully harden. Always use the exact ratio from the manufacturer and measure carefully.
Can I scale a ratio to a target amount of one part?
Yes. If you fix the amount of resin you have, the hardener needed is resin times B divided by A, and vice versa. Enter the total you want and this tool gives both parts; to fix one part, set the total to that part times (A plus B) divided by its ratio number.
Sources and notes
- The split is a direct proportion of the total batch by the ratio you supply.
- Use the exact mix ratio and measurement basis from your resin's technical data sheet; this tool does not assume a product.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.