Countertop epoxy calculator

Countertop systems usually go on in two stages: a thin base or color coat, then one or more clear or veined flood coats (the thick, self-levelling top layer). Coating bare wood such as butcher block? Add a seal coat first.

How countertop coverage is worked out

Counters are measured in square feet, but epoxy is sold by volume, so the calculator works out each part of the job separately. The flat top gets the full flood coat. The exposed edges and the backsplash are vertical, so they only hold a thin film — about 1/32 in (0.8 mm). And every foot of edge the resin runs over loses some as drips, which the calculator counts from the edge length rather than as a percentage. The waste allowance is left for what stays in the bucket.

flood coat = run × depth × coat thickness × coats
edge film = edge length × edge thickness × 1/32 in × coats
backsplash film = splash length × splash height × 1/32 in
drips = edge length × 1.25 fl oz per ft × (coat thickness ÷ 1/8 in) × coats
base coat = (top + edges + splash) × base thickness
total = (flood + films + drips + base) × (1 + waste) + seal coat
1 gallon ≈ 12.8 sq ft at 1/8 in · 1/8 in ≈ 10 fl oz per sq ft

A 10 ft run of standard 25.5 in counter is 21.25 sq ft; a 1/8 in flood coat over it is about 1.66 gallons. The 1.5 in front edge holds about 3 fl oz of film, a 4 in backsplash about 8 fl oz, and 10 ft of front edge drips about 12.5 fl oz. With 5% for the bucket that comes to about 1.93 gallons — two 1-gallon kits with very little spare. TotalBoat’s TableTop kit is a useful cross-check: it lists 12.8 sq ft per gallon at 1/8 in, the same figure the math gives (231 cubic inches in a gallon ÷ 1/8 in ÷ 144).

Worked examples: How much epoxy for 30 sq ft of countertop, How much epoxy for a 50 sq ft kitchen countertop, How much epoxy to coat a kitchen island and How much epoxy for a 5 ft bathroom vanity top.

Base coats, flood coats and oz per sq ft

Countertop brands often describe coverage in fluid ounces per square foot rather than thickness. The two are the same thing: 1/8 in is about 10 fl oz per sq ft, 1/16 in about 5, and 1/32 in about 2.5. Some brands plan a rolled or hand-spread color coat at roughly 3–4 fl oz per sq ft, and heavier “dirty pour” or veined flood coats at more — so the calculator shows the rate for your base and flood coats, before drips and waste, to compare against the instructions in your kit. Pick the base coat and flood-coat thickness your system calls for; they vary by brand, and coating resins usually have a maximum per coat (TotalBoat lists 1/4 in for its TableTop).

Seal coat on wood tops

Laminate and old sealed counters don’t need a seal coat — they need cleaning, sanding and whatever primer your kit specifies. Bare wood does: butcher block, plywood and MDF are full of air that bubbles up into a flood coat. The calculator uses about 1 fl oz per sq ft (0.32 L/m²) for closed-grain wood such as maple butcher block, 2 fl oz (0.64 L/m²) for open grain such as oak, and 4 fl oz (1.3 L/m²) for end grain or spalted wood, over the top, backsplash and edges, plus 5% for the cup and brush. End-grain butcher block often takes two seal coats.

Tips for counters

• Measure L-shaped counters as two straight runs and add them; don’t double-count the corner square.
• Leave out the sink cut-out only if it’s large — a standard sink opening is only a few square feet, and resin runs into the opening anyway.
• Tape and paper the cabinets and floor. Countertop epoxy drips steadily off the front edge for a while after the pour.
• Mix in batches you can spread before they start to thicken, and pour them back to back into the same layer so the wet edges merge — the batch figure under More options splits the job for you.
• Wear nitrile gloves and keep uncured epoxy off your skin: WEST SYSTEM’s safety guide warns that repeated contact can cause sensitization, an allergy that gets worse with each exposure.
• Epoxy surfaces are not heat-proof. Use trivets for hot pans — many products list a heat limit well below cookware temperatures.