Resin and Epoxy Volume Calculator

1. Enter the length and width of your mould or surface in centimetres.
2. Enter the pour depth, the thickness of resin you want.
3. Choose the mix ratio printed on your resin, such as 1:1 or 2:1.
4. Set a small margin for waste, then read the total resin and the part A and part B amounts.

A resin volume calculator tells you how much epoxy you need to fill a mould or coat a surface, then splits that total into the two parts you mix together. Mixing too little leaves a half-filled pour, while mixing too much wastes expensive resin and can overheat in the cup.

Because epoxy is measured by volume or weight in a fixed ratio, getting both the total and the split right is the difference between a clean cast and a sticky, wasted one.

1. Multiply length by width by depth in centimetres to get the volume in millilitres.
2. Add a margin for cup residue and small spills.
3. Split the total by your mix ratio into part A and part B.
4. Estimate weight by multiplying millilitres by about 1.1.

One cubic centimetre equals one millilitre, so working in centimetres gives volume in millilitres directly, which is how resin is usually measured.

You are casting a 30 by 20 centimetre tray to a depth of half a centimetre. The volume is 30 times 20 times 0.5, which is 300 millilitres. Adding a 10 percent margin brings it to 330 millilitres. At a 1:1 ratio you measure 165 millilitres of resin and 165 of hardener; at 2:1 it becomes 220 and 110. For a round mould, use pi times the radius squared times the depth instead of length by width.

Pour Depth

Depth scales the volume directly, and deep pours also limit how much you can mix at once before the resin overheats.

Surface Area

Larger moulds and tabletops need proportionally more resin, so measure carefully before you buy.

Mix Ratio

The ratio does not change the total but decides how that total splits between resin and hardener.

Waste and Residue

Some resin always clings to cups and sticks, which is why a small margin keeps you from coming up short.

Different epoxies use different ratios; always follow the one on your bottle.

Getting the ratio wrong is the most common cause of resin that stays soft or tacky, so measure each part precisely.

Planning a Pour

Know how much to buy and mix before you start, so you are not caught short mid-pour.

Deep Casts

Plan layered pours for deep moulds, working out the resin for each layer separately.

Coating Surfaces

Estimate a thin seal coat for a tabletop or artwork at a shallow depth.

1. Guessing the Mix Ratio

An off-ratio mix may never fully cure, leaving a soft or sticky surface. Follow the bottle exactly.

2. Mixing Too Much at Once

A large deep mix overheats and can smoke or crack; pour in layers for depth.

3. Forgetting Waste

Resin left in the cup means you need a little more than the bare volume; add a margin.

4. Ignoring Round Shapes

For circular moulds, use pi times radius squared times depth, not length by width.

The volume maths is exact for a rectangular pour, and the split follows your ratio precisely. Real needs vary a little with waste and the exact density of your resin.

Multiply length by width by depth in centimetres to get millilitres. A 30 by 20 cm surface at 0.5 cm deep needs 300 mL before adding a margin for waste.

Divide the total by your mix ratio. At 2:1, two thirds is resin and one third is hardener, so 300 mL becomes 200 mL of part A and 100 mL of part B.

Use the ratio printed on your resin, commonly 1:1, 2:1 or 3:1 by volume. Mixing off-ratio can leave the resin soft or tacky.

Use pi times the radius squared times the depth. For a 10 cm radius at 2 cm deep, that is about 628 mL.

Some resin always stays in the mixing cup and on your stick. A margin of about 10 percent stops you running short during a pour.

Most epoxy resins are close to 1.1 grams per millilitre, so 300 mL weighs roughly 330 grams. Check your product for its exact density.

No. Deep pours generate heat as they cure and can crack or smoke. Many resins limit a single layer, so deep moulds are poured in stages.

Yes. Warmth speeds curing and lowers viscosity, while cold slows curing and can leave bubbles. Follow your resin working-temperature range.

No. The calculator runs entirely in your browser and nothing you enter is stored or sent anywhere.

• Epoxy resin (Wikipedia).
• Resin casting (Wikipedia).
• Volume of a cuboid (Wikipedia).