How to calculate how much epoxy you need
Every epoxy estimate comes down to one idea: volume. You're filling a three-dimensional space, and resin is sold by volume. Find the volume of the space you're filling, convert it to gallons, and add a little for waste.
One US gallon equals 231 cubic inches. So a pour measuring 60 × 30 × 0.125 inches is 225 cubic inches, or about 0.97 gallons before waste. The calculator above does this for you and rounds to a sensible purchase size.
Table tops & coatings
For a flood or seal coat, the "depth" is your coating thickness. A standard flood coat is about 1/8 inch. Thinner seal coats go down around 1/16 inch and stretch much further per gallon.
Deep pours
For a solid block or mold, use the full depth. Most deep-pour epoxies cap a single lift at roughly 2 inches to control heat — taller pours are done in stages. See our guide on deep pours without bubbles.
River tables
The most common mistake is measuring the whole slab. You only fill the open river channel, so measure the channel's length and its average width (live edges taper, so average the wide and narrow points), then the pour depth.
Epoxy coverage reference
How far one US gallon goes at common thicknesses:
| Application | Thickness | Coverage / gallon |
|---|---|---|
| Seal coat | 1/16 in | ~25 sq ft |
| Flood / table top | 1/8 in | ~12–13 sq ft |
| Thick coat | 1/4 in | ~6 sq ft |
| Deep pour (single lift) | up to ~2 in | by volume |
Frequently asked questions
How do I calculate how much epoxy I need?
Multiply length × width × depth in inches for cubic inches, then divide by 231 for US gallons. For a coating, the coating thickness is your depth. Add about 10% for waste.
How many square feet does a gallon of epoxy cover?
At a 1/8 inch flood coat, one gallon covers roughly 12–13 sq ft. At a 1/16 inch seal coat, about 25 sq ft.
How much epoxy do I need for a river table?
Measure only the open river channel — length × average width × depth — divide by 231 for gallons, then add ~10% for waste.
Why add a waste factor?
Resin clings to the mixing container, soaks into porous wood, and is lost to drips and leveling. A 5–10% buffer keeps you from running short mid-pour.