Disclosure: BigEpoxy.com may earn a commission if you buy through links on this page, at no extra cost to you. Coverage numbers come from manufacturer data sheets; the math is standard unit conversion.
There are two different questions hiding in this one:
- Floor and countertop coatings: how many square feet does a gallon (or kit) cover at a given thickness?
- Thick pours (tabletops, river tables): how many gallons fill a given area at a given depth?
Both come down to the same fact: one US gallon is 231 cubic inches. Everything below follows from that.
The one number to remember: 1,604
Spread 231 cubic inches over a film 1 mil (0.001″) thick and you get:
231 ÷ (144 sq in per sq ft × 0.001 in) = 1,604 sq ft per gallon at 1 mil wet
So:
Coverage (sq ft per gallon) = 1,604 ÷ wet film thickness in mils
| Wet film thickness | Coverage per gallon |
|---|---|
| 4 mils | ~401 sq ft |
| 6 mils | ~267 sq ft |
| 8 mils | ~200 sq ft |
| 10 mils | ~160 sq ft |
| 16 mils | ~100 sq ft |
| 1/16″ (62.5 mils) | ~25.7 sq ft |
| 1/8″ (125 mils) | ~12.8 sq ft |
| 1/4″ (250 mils) | ~6.4 sq ft |
Wet vs. dry film: why solids matter
What stays on the floor after cure is the dry film:
Dry film thickness = wet film thickness × solids by volume
A water-based kit loses its water as it dries. A 100%-solids epoxy keeps essentially all of it.
Check it against a real product
Rust-Oleum’s EpoxyShield TDS lists about 52.6–52.8% solids by volume and a recommended 3.0–3.5 mils dry per coat. The 1-car pouch holds 92.5 + 27.5 = 120 fl oz (0.94 gal) and covers about 250 sq ft of smooth concrete.
- Wet film: 1,604 × 0.94 ÷ 250 ≈ 6.0 mils
- Dry film: 6.0 × 0.527 ≈ 3.2 mils, right inside the TDS range.
That’s why a “250 sq ft” water-based kit leaves a much thinner film than a high-solids product. Rust-Oleum’s RockSolid is 96% solids (RockSolid TDS), so nearly everything you roll on stays as film.
Garage floor coverage: published numbers
| Product | Coverage (manufacturer) | Approx. per sq ft |
|---|---|---|
| Rust-Oleum EpoxyShield 1-car kit (~0.94 gal) | ~250 sq ft smooth; 125–200 rough | ~0.0038 gal/sq ft smooth (~0.48 fl oz) |
| Rust-Oleum RockSolid, per pouch | 200–250 sq ft; TDS: 4.9–6.2 m²/L | — (see TDS) |
| Seal-Krete Epoxy-Seal Pro kit | up to 250 sq ft smooth; 125–200 rough | — |
| BEHR 1-Part Epoxy No. 900 | 400–500 sq ft/gal smooth; 300–400 rough | 0.002–0.0025 gal/sq ft smooth |
| ArmorGarage Polyaspartic 80 (pro-grade) | ~250 sq ft/gal | 0.004 gal/sq ft |
Rough concrete eats coating. EpoxyShield’s coverage drops from 250 to 125–200 sq ft on rough or porous slabs, which means 25%–100% more material.
Tabletops and casting: per square foot at depth
For thick pours, flip the formula:
Gallons = length (in) × width (in) × depth (in) ÷ 231
Per square foot (144 sq in):
| Depth | Gallons per sq ft | Fluid ounces per sq ft |
|---|---|---|
| 1/16″ | 0.039 | ~5.0 |
| 1/8″ | 0.078 | ~10.0 |
| 1/4″ | 0.156 | ~20.0 |
| 1/2″ | 0.312 | ~39.9 |
| 1″ | 0.623 | ~79.8 |
Real-world check: TotalBoat’s TableTop Epoxy TDS lists 6.4 sq ft at 1/4″ per 1-gallon kit, which matches 1,604 ÷ 250 mils = 6.4. Its instructions also say 1 oz of mixed epoxy covers about 6.5 sq in at 1/4″.
Add a margin
Formula numbers are minimums. Add:
- 10% for floors (roller absorption, tray waste, cut-in).
- 10–20% for tabletops and rivers (seal coat, drips over the edges, leaks and absorption into wood). TotalBoat says to always seal-coat wood first; its seal coat covers roughly 24 sq ft per gallon kit.
Quick calculator
Use our epoxy calculator. The floor tab takes sq ft coverage from your data sheet, and the river table tab handles depth-based volume.
FAQ
How much epoxy per square foot for a garage floor? For a typical water-based DIY kit, about 0.004 gallons (~0.5 fl oz) per sq ft per coat on smooth concrete, based on EpoxyShield’s 250 sq ft per 0.94-gallon kit. Rough concrete needs more.
How much epoxy per square foot at 1/8 inch? About 0.078 gallons (10 fl oz) per sq ft, or 12.8 sq ft per gallon.
How many square feet does a gallon of epoxy cover? It depends on thickness: ~267 sq ft at 6 mils wet, ~160 sq ft at 10 mils, ~12.8 sq ft at 1/8″.
Sources
- NIST Handbook 44 (US gallon = 231 cubic inches).
- Rust-Oleum EpoxyShield TDS ESH-39 (solids, film thickness, kit contents) and RockSolid TDS RSD-10 (fetched October 2026).
- Seal-Krete Epoxy-Seal Pro TDS; Behr No. 900 product page (fetched October 2026).
- ArmorGarage Polyaspartic 80 TDS (fetched October 2026).
- TotalBoat TableTop Epoxy Instruction Sheet & TDS (fetched October 2026).