How much resin do I need?
Resin fills a space, so the amount you need is the volume of your piece: its area multiplied by how thick the resin will be. A flat coat on a 12 × 12 in panel at 1/8 in uses about 10 fl oz (295 ml). A useful rule for coatings: about 10 fl oz per square foot at 1/8 in, or 3 ml for every 10 cm² at 3 mm.
Then mix a little more than that. Some resin always stays in the cup and on the stirrer, and a coating runs over the edges. The calculator adds 10% by default; use 15–20% for coats that drip off the sides.
Resin needed for common pieces
Total of resin and hardener for one piece, before the extra allowance.
| Piece | Mixed resin |
|---|---|
| Round coaster, 4 in (10 cm), 1/4 in deep | 1.7 fl oz (51 ml) |
| Square coaster, 4 × 4 in, 1/4 in deep | 2.2 fl oz (66 ml) |
| Tray or panel coat, 8 × 12 in, 1/8 in | 6.6 fl oz (197 ml) |
| Art panel, 12 × 12 in, 1/8 in | 10.0 fl oz (295 ml) |
| Canvas, 16 × 20 in, 1/8 in | 22.2 fl oz (655 ml) |
| Canvas, 24 × 36 in, 1/8 in | 59.8 fl oz (1770 ml) |
The formula in plain English
- Rectangle = length × width × depth.
- Circle = 3.14 × radius × radius × depth (the radius is half the diameter).
- Any mould = the weight of water that fills it: 1 g of water is 1 ml.
- Volume conversions: 1 cubic inch = 0.554 fl oz = 16.4 ml; 1 cm³ = 1 ml.
- Resin and hardener = the total split by your kit's ratio. At 2:1, two thirds is resin and one third is hardener.
- Cost per piece = resin used × kit price ÷ kit size, plus supplies, packaging, your time and a failure allowance.
Worked example: four round coasters
A set of four 4 in round coasters, 1/4 in deep, with a 1:1 resin from an $80 one-gallon kit (the calculator's defaults):
- Each coaster: 3.14 × 2 × 2 × 0.25 = 3.14 cubic inches = 1.74 fl oz (51.5 ml)
- Four coasters plus 10% extra: 1.74 × 4 × 1.1 = 7.66 fl oz to mix
- At 1:1 by volume: 3.83 fl oz of resin and 3.83 fl oz of hardener
- Resin cost: $80 ÷ 128 fl oz = $0.625 per fl oz, so $1.20 per coaster
- Costs each: resin $1.20 + supplies $0.50 + packaging $0.75 + labour $2.81 (45 minutes at $15/hour across four coasters) = $5.26
- Plus 10% for failures: $5.79 cost per coaster
- Doubled (100% markup) and grossed up for US Etsy fees: sell at $13.28 each
The resin itself is the smallest cost here. Your time is the largest, which is why pouring several pieces in one session pays off.
Mixing by volume or by weight
Every kit states its ratio and how to measure it. Many art resins are 1:1 by volume: equal amounts in graduated cups. Others give a weight ratio such as 100:45, measured on a scale. The two aren't interchangeable, because resin and hardener have different densities, so measure the way your kit says. Choose a custom ratio by weight in the calculator for kits like these.
How deep can you pour?
Coating (art) resins are made for thin layers, typically up to about 1/8 in (3 mm) at a time. Pour them thicker and they can overheat, yellow or crack. Casting and deep-pour resins cure more slowly and handle much deeper pours, often 1–2 in. If your piece is deeper than your resin allows, the calculator tells you how many layers to pour, letting each one set before the next.
FAQs
How much resin do I need for coasters?
About 1.7 fl oz (51 ml) for a 4 in round coaster 1/4 in deep, or 7.7 fl oz to mix for a set of four with 10% extra. A 4 in square coaster at the same depth takes a little more, 2.2 fl oz.
How much resin per square foot?
About 10 fl oz (295 ml) per square foot at 1/8 in, before extra. Double it for 1/4 in, which most coating resins need to pour as two layers.
How do I work out the volume of a mould?
Fill it with water to where the resin will stop, pour the water into a cup on a kitchen scale and note the weight. 1 g of water is 1 ml. Dry the mould completely before pouring resin. Choose “Mould” and enter the weight.
How much pigment or mica powder should I add?
A little goes a long way: often 1–2% of the resin's weight is enough, and most resins accept up to about 6% before the cure suffers. Enter a percentage and the calculator shows the grams.
Why mix more resin than the piece holds?
Resin clings to the cup, the stirrer and the sides of the mould, and coatings run off the edges. Running short halfway through a pour leaves a visible line, so it's cheaper to mix 10–20% extra.
Are Etsy fees included?
Yes, with typical fees for your currency, including VAT on fees for UK sellers who aren't VAT registered. Choose “No fees” for craft fairs or direct sales.
What is this calculator for?
Art and small craft pieces: coasters, trays, resin art panels, jewellery and moulded pieces. Always follow your resin's own instructions, and work with gloves in a well-ventilated room.
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