Epoxy mix ratio calculator
Resin and hardener for any amount, from the ratio printed on your own bottle — in millilitres and grams at once, and with the gap between the two conventions shown rather than hidden.
INPUTS
The ratio on your bottle
Usually deep pour, casting and general-purpose epoxy. The commonest ratio after 1:1, and the one where the volume-versus-weight gap bites most often in practice.
: 1
And the bottle means it
The one thing a label often fails to say. If yours does not, check the technical data sheet — guessing is the
mistake this page exists to prevent.
What do you know?
ml
Measured in
Your bottle states 2:1 by volume, which is 2.20:1 the other way — the same mix, two different numbers, because resin is the denser of the two. Measure to the printed figure on a scale and you get 177.8 g of hardener where you needed 166.7, 7% too much. Either way there is unreacted material left in the piece, and it stays tacky.
The ratio is not a recipe you can lean on. Epoxy and hardener react in fixed proportion, so anything left over after the reaction has finished has nothing to bond to and simply stays in the piece as a soft, sticky contaminant. Extra hardener does not speed the cure up and extra resin does not make it harder — both give you the same result, which is a surface that never stops being tacky.
Do not adjust the ratio to change the cure. Adding hardener does not make epoxy set faster and adding resin does
not make it harder — both leave unreacted material in the piece, which is a surface that stays sticky rather
than one that eventually gets there. If you need it faster, warm the room.
RESULTS
Hardener
166.7 g
166.7 ml 31.3% of the mix by weight
Measure out
| Part | By volume | By weight |
|---|---|---|
| Resin | 333.3 ml | 366.7 g |
| Hardener | 166.7 ml | 166.7 g |
| Mixed | 500.0 ml | 533.3 g |
Stated by volume
2: 1
Same mix, by weight
2.20: 1
Measure to the printed 2:1 on a scale and you get
177.8 g of hardener where you needed
166.7 — 7%
too much. That is the whole reason this page exists: resin is
1.1 g/ml and hardener is 1, so the two conventions are not the same mix. Once you know which
one your bottle means, the table above is correct in either unit.
Print the pour-depth card
Maximum pour depth and cure windows by resin type — the number that cracks a casting. Free.
How this is worked out
The ratio on a bottle is parts of resin to one part of hardener, and it is a fixed property of the chemistry rather than a setting. The awkward part is that it is a bare number: "2:1" means one thing measured in a jug and another on a scale, because resin is about 1.1 g/ml and hardener about 1. So this tool asks the printed number AND what the label means by it, converts to the other convention through those two densities, and reports both — because the maker's instrument and the bottle's convention are usually not the same thing, and nothing on the label warns them. Everything is resolved to a total volume first, whichever end you come in at, then split by the by-volume ratio and weighed through each part's own density. The misread figure is shown as an output rather than a footnote: at 2:1 the gap is about 7% of the hardener, and it widens as the ratio does.
by weight = by volume × 1.1 ÷ 1 resin is the denser of the two
by volume = by weight × 1 ÷ 1.1
resin = total × ratio ÷ (ratio + 1) ratio applied by VOLUME
hardener = total − resin
grams = each part × its own density 1.1 and 1 g/ml
1:1 → 1.10:1 · 2:1 → 2.20:1 by weight
Questions makers ask
How do I mix resin and hardener?
In the exact proportion the bottle states, measured with something that repeats. For 500 ml of a 2:1 system quoted by volume, that is 333 ml of resin to 167 ml of hardener, or 366.7 g to 166.7 g on a scale. Then stir slowly for three full minutes, scraping the walls and the bottom of the cup — unmixed resin clinging to the side is unmixed resin in the finished piece.
Is 2:1 by volume the same as 2:1 by weight?
No, and this is the thing that catches people. Resin runs about 1.1 g/ml and hardener about 1, so a 2:1 mix stated by volume is 2.20:1 by weight, and stated by weight it is 1.82:1 by volume. Take the printed number to the wrong instrument and you are out by about 7% on the hardener — which is comfortably enough to leave a piece tacky forever.
What happens if I add too much hardener?
The ratio is not a recipe you can lean on. Epoxy and hardener react in fixed proportion, so anything left over after the reaction has finished has nothing to bond to and simply stays in the piece as a soft, sticky contaminant. Extra hardener does not speed the cure up and extra resin does not make it harder — both give you the same result, which is a surface that never stops being tacky.
How much hardener do I add to resin?
Whatever the ratio gives, and never a splash more. If you have a fixed amount of resin left and want to use it up, set the tool to "Resin I have" and it works out the hardener for you rather than the other way round. That is the usual real situation — the bottles never run out together. If you are starting from a project instead of a bottle, <a href="/resin/epoxy-calculator">the epoxy calculator</a> works out the total from the shape and depth first.
Which ratio does my resin use?
Table top / coating epoxy is usually 1:1 and deep pour / casting epoxy 2:1, with 3:1 and 4:1 appearing on laminating and marine systems. But the ratio is a property of the specific product, not of the category — check your own bottle or its technical data sheet, and check whether it says by volume or by weight while you are there.
Can I mix resin by eye?
Not at any ratio, and least of all at the high ones. At 4:1 the hardener is only 20% of the mix, so being a little generous with it is proportionally enormous — which is exactly why marine systems ship with pump dispensers. A kitchen scale reading to 1 g costs less than one ruined pour.
Do I measure resin by weight or by volume?
Weight, if you have the choice. A scale repeats, a graduated cup does not, and what stays clinging to the sides of a jug is a real share of a small mix. The only thing that matters is that you use the figure matching your instrument — this tool gives both, from whichever one your bottle states.
Does UV resin have a mix ratio?
No. UV resin is one part — no hardener, nothing to measure, and it stays liquid in the bottle until light hits it. If that is what you have, none of this page applies.
The same ratio, both ways
Every printed ratio means two different mixes depending on what the label meant by it, and the gap widens as the ratio does. Read your bottle before you read this table — but if it does not say, the last column is what you are gambling.
| Printed ratio | If it means volume, by weight | If it means weight, by volume | Hardener error if you guess |
|---|---|---|---|
| 1:1 — table top, coating and most art resins | 1.10:1 | 0.91:1 | 5.0% |
| 2:1 — deep pour, casting and general-purpose epoxy | 2.20:1 | 1.82:1 | 6.7% |
| 3:1 — laminating and some coating resins | 3.30:1 | 2.73:1 | 7.5% |
| 4:1 — marine and laminating systems | 4.40:1 | 3.64:1 | 8.0% |
Read before your next batch
- How to make resin art Buy the right resin for the depth you are pouring, weigh both parts rather than eyeballing them, and leave it alone once it is poured. Almost every first-batch failure is one of those three.
- UV resin One part, no hardener, no measuring, and set in about a minute. It is a genuinely different product from two-part epoxy, and its limits are not the ones you would guess.
- Resin vs epoxy: which type to buy Four products share the word, and the one thing that separates them is how deep you can pour them. Pick by that, and everything else follows.
- Deep pour vs table top epoxy Two clear liquids that look identical in the bottle, with maximum pour depths about ten times apart. Going past the wrong one is a heat problem, not a patience problem.