How much epoxy resin do I need
Calculating the right amount avoids the two most expensive mistakes: running short mid-pour or wasting product. Here is the formula, the recommended margin and an example; and if you prefer the shortcut, the calculator does it for you in seconds.
The formula to calculate epoxy resin
The calculation starts from the volume of the piece: area x depth. Area depends on the shape (rectangle: length x width; circle: π x radius²). That volume, multiplied by the resin density (between 1.05 and 1.20 g/ml depending on the product), gives the total mix weight in grams. Finally it is split into part A and part B according to the product ratio (2:1, 3:1…).
By surface or by volume
If you are coating a flat surface (countertop, painting, floor), think in kg per m²: around 1.1-1.2 kg of mix per m² for every millimeter of thickness. If you are filling a volume (river table, mold, deep piece), use the real volume in cm³ and convert it with the density.
The waste margin
There is always resin stuck in the cup, the stir stick and the gloves. Add a 10% margin by default, or 15% if it is your first project. It is better to have a little left over than to come up short: a late second batch can leave a visible line between layers.
Example: rectangular tray
- Dimensions
- 40 × 25 cm
- Depth
- 1 cm
- Volume
- 1,000 cm³
- Density
- 1.10 g/ml
- Mix (+10%)
- ≈ 1,100 g
Note: For your specific piece, the calculator applies the real product density and splits it into layers if needed.
Want the exact amount for your piece, with the A:B ratio and layer plan?
Calculate my projectFrequently asked questions
How do you calculate epoxy resin step by step?
1) Calculate the area (length x width). 2) Multiply by the depth for the volume. 3) Multiply the volume by the density (~1.1 g/ml) for the grams. 4) Add a 10% margin. 5) Split into part A and part B by the product ratio.
How much does a liter of epoxy resin weigh?
A liter of mix weighs roughly 1.1 kg, depending on the resin density (1.05-1.20 g/ml). That is, 1,000 cm³ equals about 1.1 kg of mixed resin.
Is it better to have too much or too little?
Too much. Coming up short mid-pour forces a second batch that can leave a visible seam. A 10% margin is usually enough.