How this mixing calculator works
Enter how much mixed epoxy you need and the ratio printed on your resin, and the calculator splits the batch into Part A (resin) and Part B (hardener). A 2:1 ratio means two measures of resin for every one of hardener — so a 32 fl oz (950 ml) batch is 21.3 oz of A and 10.7 oz of B. The ratio fields accept halves, so 2.5:1 and similar ratios work too.
Volume or weight?
This calculator splits by volume, which is how most hobby and tabletop epoxies are specified. Some brands list a weight ratio as well — and it's usually different from the volume ratio, because resin and hardener have different densities. Never mix a volume ratio on a scale or vice versa; use the method the label states.
Why ratio accuracy matters
Epoxy cures by a precise chemical reaction — there is no 'more hardener cures faster'. Off-ratio batches stay soft, sticky or brittle permanently, and no amount of waiting fixes them. Stay within about 5% of the stated ratio: use graduated mixing cups at eye level, and for small batches a cheap 0.1 g kitchen scale with the brand's weight ratio is the most accurate route.
Mixing technique
Pour A first, add B, and stir slowly for 3–5 minutes, scraping the cup sides and bottom repeatedly — unmixed resin hides there and becomes a sticky streak in the cured piece. For critical pours, transfer to a second clean cup and stir again ('double cup' method). Mix only what you can use within the resin's pot life.