Practical guide 3 min read
How much epoxy resin do you need?
Work out resin for coasters, molds, tabletops and river tables, measure odd shapes with water, and know when a pour needs layers.
New
Tool
Resin Calculator
Enter the size of your mold or surface and how deep you’ll pour. You get the total to mix, Part A and Part B for your resin’s mix ratio, and how many layers the pour needs so it doesn’t overheat.
Loading Resin Calculator…
Runs in your browser. What you enter is saved on this device only.
How to use the Resin Calculator
- Pick the shape: rectangle or tabletop, circle, river table, sphere or dome. For an odd shape, fill the mold with water and weigh the water.
- Enter the measurements, the depth you’ll pour and how many pieces you’re making.
- Choose coating or deep pour resin and the mix ratio from its label.
- Mix the Part A and Part B amounts shown, over the number of pours shown.
How it’s calculated
Volume is length × width × depth for rectangles and river tables, πr² × depth for circles, 4⁄3πr³ for spheres and half that for domes, times the number of pieces, plus your extra for waste. Parts A and B split the total by the mix ratio. For ratios by weight, the volume is turned into grams with the mixed resin’s density, about 1.1 g/ml for most epoxies. Pours = depth ÷ your resin’s maximum pour depth, rounded up.
Questions
How much resin do I need for a tabletop?
A 1/8 inch (3 mm) coat takes 18 cubic inches per square foot, about 10 fl oz (295 ml). A 3 × 6 foot table is 18 square feet: about 180 fl oz, or 1.4 gallons, before extra for drips over the edges.
How do I measure a mold with an odd shape?
Fill it with water, then weigh the water on a kitchen scale or pour it into a measuring jug, and enter it with the “Measure with water” shape: 1 gram of water is 1 ml. Dry the mold completely before pouring resin, because water spoils the cure.
Why pour in layers?
Epoxy gives off heat as it cures, and too thick a pour can overheat, yellow, crack or trap bubbles. Coating resins are usually made for about 1/8 inch (3 mm) per coat, deep pour resins for 1 to 2 inches (2.5–5 cm) or more. Use your product’s maximum and let each layer set as its instructions say.
Should I measure resin by volume or by weight?
Whichever the label gives. Ratios like 1:1 and 2:1 are usually by volume; ratios like 100:45 are by weight. The two parts have different densities, so measuring a volume ratio on a scale (or the other way round) mixes it wrong, and it may never fully cure.
Are my numbers saved?
On this device only. Each calculator remembers what you last entered, in your browser, so you can pick up where you left off; nothing is sent to our server. Reset puts the starting values back.
Do I need an account?
No. Every craft calculator is free to use without signing in, with no limits.
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