Epoxy Pour Volume Calculator
Volume for a river table pour, how many layers the depth limit forces, and why a 2:1 mix by volume is 2.35:1 on a scale.
Densities vary between products — take them from the technical data sheet rather than these defaults, and take the depth limit from it too. Nothing here substitutes for the manufacturer's instructions. Nothing is uploaded.
2:1 by volume is 2.35:1 by weight
Resin and hardener are not the same density — resin is typically around 1.15 g/mL and hardener around 0.98. So a product stating 2:1 by volume wants 2.35:1 on a scale, and measuring 2:1 by weight instead puts you 17% out.
| Stated by volume | Densities | The same ratio by weight | Error if confused |
|---|---|---|---|
| 1:1 | 1.1 / 1 | 1.100:1 | 10.0% |
| 2:1 | 1.15 / 0.98 | 2.347:1 | 17.3% |
| 3:1 | 1.13 / 0.96 | 3.531:1 | 17.7% |
| 4:1 | 1.14 / 0.97 | 4.701:1 | 17.5% |
Epoxy does not tolerate being approximately right. The two parts react in fixed proportion, and whatever is in surplus has nothing to bond with — it stays in the cured resin as an unreacted softener. The result is a pour that stays tacky, cures soft, or reads as fine for a week and then sinks. And nothing about a 17% surplus looks wrong while you are stirring it. Where the two densities happen to match, the ratios coincide and the distinction disappears, which is why some products publish one figure and others publish two.
A deep pour goes in layers
Curing epoxy gives off heat, and a deep pour holds that heat in rather than shedding it. Past a product's stated depth per layer it can crack, yellow or scorch. The 60 by 14 by 2 inch river below needs 17.89 litres once the wood displacing 35% of the void is allowed for — and at a three-quarter-inch limit that is three pours, not one.
| Max depth per pour | Pours needed | Each pour |
|---|---|---|
| 0.5 in | 4 | 4.47 L |
| 0.75 in | 3 | 5.96 L |
| 1 in | 2 | 8.95 L |
| 1.5 in | 2 | 8.95 L |
| 2 in | 1 | 17.89 L |
The limit is a physical property of the product rather than a cautious suggestion — deep-pour formulations exist precisely because they cure slowly enough to shed the heat, and they are slower and dearer for that reason. Allowing for the wood already in the void matters too: ignoring it here would have you mix 27.53 litres instead of 17.89.
How to use
- Enter the void dimensions and how much is already filled by wood.
- Add the maximum pour depth from the data sheet.
- Read the volume and the number of pours.
- Check the mix ratio in the other unit before you measure.
Frequently asked questions
Is a 2:1 mix ratio the same by weight and by volume?
No. Resin is denser than hardener — typically about 1.15 g/mL against 0.98 — so 2:1 by volume is 2.35:1 on a scale. Measuring 2:1 by weight when the product meant volume puts you 17% out.
What happens if I get the ratio wrong?
The two parts react in fixed proportion, so whatever is in surplus has nothing to bond with and stays in the cured resin as an unreacted softener. The pour stays tacky, cures soft, or reads as fine for a week and then sinks. Nothing about a 17% surplus looks wrong while you are stirring it.
Why do some products publish one ratio and others two?
Because where the densities happen to match, the two ratios coincide and one figure is enough. Where they do not, the manufacturer has to state which method the number applies to — and that is the line worth reading twice.
Can I pour a deep void in one go?
Usually not. Curing epoxy gives off heat and a deep pour holds it in rather than shedding it, so past the stated depth per layer it can crack, yellow or scorch. A two-inch river at a three-quarter-inch limit is three pours.
What is deep-pour epoxy then?
A formulation that cures slowly enough to shed its own heat, which is why it allows greater depths and why it is slower and dearer. The depth limit on any product is a physical property of the chemistry rather than a cautious suggestion.
How do I allow for the wood in the void?
Estimate the share of the space it occupies and enter it. On a live-edge river that is commonly a third or more, and ignoring it means mixing considerably more epoxy than the void can take — which matters, because mixed epoxy cannot be saved.
Should I mix it all at once?
No — mix each pour separately. A large batch generates more heat in the pot and gives you less working time, which is the same problem as a deep pour in a different container.
Does this send anything anywhere?
No. Every figure is computed in your browser, and nothing is uploaded or stored.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.