What to measure
How to use the epoxy calculator
Choose a rectangle or a circle and enter the length, width and pour depth. Lengths can be in feet or inches; most coatings are 1/8 inch, which you can type as 0.125 in. Pick your kit’s mix ratio from its label to see how much resin and hardener to measure. Add the kit’s price per mixed gallon to see the cost.
For a river table, enter the channel between the slabs, not the whole table.
The formula
- Cubic inches = length × width × depth (all in inches)
- Gallons = cubic inches × (1 + extra %) ÷ 231
- Resin = gallons × resin parts ÷ (resin + hardener parts)
Worked example: 2 × 4 ft table top, 1/8 in flood coat
- 24 × 48 × 0.125 = 144 cu in
- 144 × 1.10 ÷ 231 = 0.69 gallons (88 fl oz, 2.6 L)
- At 1:1 that is 0.34 gal of resin and 0.34 gal of hardener; at 2:1, 0.46 and 0.23
Epoxy for common projects
| Project | Pour | Gallons (+10%) | Fl oz |
|---|---|---|---|
| 2 × 4 ft table top | 1/8 in | 0.69 | 88 |
| 2 × 8 ft bar top | 1/8 in | 1.37 | 176 |
| 3 × 6 ft dining table | 1/8 in | 1.54 | 197 |
| 3 ft round table | 1/8 in | 0.61 | 78 |
| River, 6 ft × 6 in | 1.5 in | 3.09 | 395 |
| River, 8 ft × 8 in | 2 in | 7.31 | 936 |
Common mistakes
- Pouring deeper than the label allows. Thick pours of coating epoxy heat up as they cure and can crack or yellow. Use the product’s maximum depth per pour and build up in layers.
- Measuring the whole table for a river pour. Only the channel holds resin. Measure its average width, and add a little for the bark edges and any gaps under the slabs.
- Mixing by weight with a volume ratio. A 2:1 ratio by volume is not 2:1 by weight. Use the measure the data sheet gives.
- Forgetting seal coats. Porous wood soaks up resin. A thin seal coat first stops bubbles, and it uses epoxy too — add it to the depth or the extra percentage.
Frequently asked questions
How much epoxy do I need for a table top?
A 2 × 4 ft top coated 1/8 inch deep holds 144 cubic inches, which is 0.62 gallons. With 10% extra for the cup and the edges, buy about 0.69 gallons (88 fl oz).
How many square feet does a gallon of epoxy cover?
About 12.8 sq ft at 1/8 inch, 6.4 sq ft at 1/4 inch and 25.7 sq ft at 1/16 inch. A gallon is 231 cubic inches, so coverage = 231 ÷ (144 × depth in inches).
How much epoxy for a river table?
Measure the river channel, not the whole table. A channel 6 ft long, 6 inches wide and 1.5 inches deep needs 3.09 gallons with 10% extra.
What is a 1:1 or 2:1 mix ratio?
The parts of resin to hardener by volume. TotalBoat TableTop mixes 1:1, so a gallon of mixed epoxy is half a gallon of each. West System 105 mixes 5:1, so a gallon is 0.83 gallons of resin and 0.17 of hardener.
Can I mix epoxy by weight instead of volume?
Only with the weight ratio from the product's data sheet. Resin and hardener weigh different amounts per gallon, so the volume ratio doesn't carry over to a scale.
How thick can I pour epoxy in one layer?
It depends on the product. TotalBoat says its TableTop epoxy handles castings up to 1 inch deep with no more than 6 fl oz per pour, and points to its deep-pour resin for larger molds. Use the label's maximum and pour thicker projects in layers.
Why add extra epoxy?
Some always stays in the mixing cup and on the stir stick, and a flood coat runs over the edges. The default 10% is a convention; raise it for edges you want fully coated.
Sources
Formulas and defaults last reviewed October 30, 2026. How we check our math.