Resin mold volume.

Worked example

Four round coasters, 10 cm across, poured 0.5 cm deep: one holds π x 5² x 0.5 = 39.27 ml, four hold 157.1 ml. Add 10% overage for 172.8 ml of mixed resin, which weighs 172.8 x 1.1 = 190.1 g. At a 1:1 volume ratio that is 86.4 ml of resin and 86.4 ml of hardener (a 2:1 ratio would be 115.2 ml and 57.6 ml).

How it works

Volume comes from the shape: rectangle length x width x depth, cylinder π x radius² x depth, sphere 4/3 x π x radius³, cone π x radius² x height / 3. One cubic centimetre is one millilitre. Weight is volume x density and the split follows the ratio, resin / (resin + hardener) of the total.

Check your product. Many casting resins are mixed by volume, but some are mixed by weight and the two do not match because resin and hardener have different densities. The ratio on your product's label governs. Also mind its maximum pour depth: deep pours generate heat as they cure, so thick pieces are usually poured in layers.

Inclusions such as dried flowers, glitter or embedded objects displace resin. Subtract their volume or leave the overage as is. Domed fills and bezels hold a bit more than a flat pour.

Sources and basis (checked 2026-10-05): standard solid geometry; 1 cm³ = 1 ml; typical cured and mixed casting-epoxy density near 1.1 g/ml as listed on manufacturer technical data sheets (confirm on yours).

FAQ

How much resin do I need to fill my mold?

Work out the volume in millilitres, add 10 to 15% extra, and mix that total. The calculator does the volume for boxes, rounds, spheres and cones.

How do I find the volume of an odd-shaped mold?

Fill the mold with water, pour the water into a measuring jug and read the millilitres. That is the volume to use.

Is resin mixed by weight or volume?

It depends on the product. Follow the label. If it says 1:1 by volume, use equal volumes of resin and hardener. If it says by weight, weigh them, because equal volumes will not be the right ratio.

How many ml is one US fluid ounce?

One US fluid ounce is 29.57 ml. The result also shows the total in US fluid ounces.

Is it safe to use resin indoors?

Use it in a ventilated area with nitrile gloves and eye protection, avoid skin contact, and follow the safety data sheet from the maker.