How to use this calculator
- Pick the shape. Use rectangle for trays, table tops and river tables, and circle for coasters and round molds.
- Enter the inside size of your mold. For a circle, enter the diameter as the length.
- Enter the depth of the pour. For a table top flood coat this is usually 1/8 inch (0.125 in).
- Choose the mix ratio printed on your resin, and keep 10% extra unless your mold is very simple.
How the calculation works
The calculator finds the volume of your pour and converts it to fluid ounces. One US fluid ounce is about 1.805 cubic inches, so:
- Rectangle: length × width × depth ÷ 1.805 = fl oz
- Circle: 3.1416 × (diameter ÷ 2)² × depth ÷ 1.805 = fl oz
It then adds your waste percentage and splits the total by the mix ratio. For example, 30 fl oz at 2:1 is 20 fl oz of resin and 10 fl oz of hardener.
Tips so you do not run short
- Mix a little more than you need. Resin left on the cup and stir stick adds up, especially in small batches.
- Seal raw wood with a thin coat first. Unsealed wood soaks up resin and causes bubbles.
- Check the maximum pour depth of your product. Table top epoxy is usually poured about 1/8 inch at a time, while deep pour resin can go thicker. Split deep pours into layers if needed.
- Always follow the mix ratio and safety sheet from your resin manufacturer.
Frequently asked questions
How much resin do I need for a 12 × 12 inch tray at 1/8 inch deep?
About 10 fl oz (300 ml) of mixed resin: 12 × 12 × 0.125 = 18 cubic inches, and 18 ÷ 1.805 ≈ 10 fl oz. Add 10% so you do not run short.
How much epoxy do I need to coat a 4 × 2 foot table top?
For a 1/8 inch flood coat you need about 80 fl oz, or roughly 0.6 gallon of mixed epoxy (48 × 24 × 0.125 = 144 cubic inches). Raw wood soaks up extra, so seal it first or add 15–20%.
Is the mix ratio by volume or by weight?
This calculator splits the total by volume, which is how most craft and table top epoxies are labeled (1:1 or 2:1). Some resins list a ratio by weight instead. Always use the ratio printed on your product.
How do I measure a river table with uneven edges?
Measure the width of the channel every 6 to 8 inches, average those numbers, and enter the average as the width. Use the inside length of your mold as the length.