Epoxy for Countertops — Gallons, Coats & Brand Rates

Quick answer

Countertop epoxy = finished sq ft × coats × 1.10 ÷ rate. One flood coat at 1/8" is the standard; bare wood wants a brushed seal coat first (≈half the flood rate per gallon). A 40 sq ft kitchen at TotalBoat's dual-verified 12.8 sq ft/gal: 3.4 gal flood + 1.8 gal seal ≈ 5.3 gal → buy 6 gallons of kit. The calculator below is preset for coating math — enter your counter's real dimensions.

Measure the top, not the room

The number one planning error is estimating from the kitchen's footprint. Measure the finished surface piece by piece — main run, island, backsplash returns — and add them. A typical layout: 30 sq ft perimeter run + 16 sq ft island + 8 sq ft returns ≈ 54 sq ft. At 1/8" flood with a 16 sq ft/gal rate: 54 × 1.10 ÷ 16 = 3.7 gallons flooded. If edges and backsplashes get coated too, they add area the same way — epoxy doesn't know a countertop from a shelf.

The two-coat schedule on bare wood

1. Seal coat — brush or squeegee a thin film (~1/16"), 24 sq ft/gal at TotalBoat's published seal rate, 48 at Primaloc's. Its jobs: stop air outgassing bubbles through the flood coat, even out porosity, and lock down loose fibers.
2. Wait the window. TotalBoat: 3 hours minimum at 70 °F. Primaloc: flood 4–6 hours after sealing. Promise: 4–5 hours, tack-free but still bonding. Inside the window the next layer chemically bonds — no sanding. Outside it, the datasheets ask for a 220–320 grit scuff first.
3. Flood coat — pour along the middle, spread with a squeegee or notched spreader, then let self-leveling do the gloss. Total film after both coats ≈ 3/16–1/4".

What the brands actually say

• TotalBoat TableTop — 12.8 sq ft/gal @ 1/8", 6.4 @ 1/4", seal ~24 (all dual-verified). Max coat 1/4". The reference rate every comparison bends around.
• Primaloc Bar & Table Top — flood 16, seal 48, both dual-verified; recoat every 4 h inside the window.
• Promise Table Top — no published coverage; 100% solids TDS; the calculator uses the labeled 12.8 theoretical. Sale-priced 1-gal kits at $61.19 make it the budget-row in the cost comparison.
• Stone Coat Countertop Epoxy — the YouTube giant; its official calculator runs gallons = L × W ÷ 20 (20 sq ft/gal basis). Premium kit pricing ($126/gal) — the comparison table prices it honestly rather than repeating the marketing.

After the pour

Total cure before real kitchen use: 5–7 days (Promise says 72 h for their formula; TotalBoat's TDS allows up to 5 days to full hardness — treat 7 days as the universal safe answer). Then the maintenance story matters more than the brand: cutting boards under knives, trivets under pans, and a UV-stable topcoat or window-film if sun hits the surface daily. Epoxy's weakness is UV and heat, not daily use — plan the kitchen around the two real enemies and the surface lasts. Once the schedule is set, the mix ratio calculator splits every batch of A and B exactly, and how much epoxy do I need walks the full two-coat volume math with more worked examples.