Flooring & Finishes

Epoxy Calculator

Find how many gallons of epoxy you need for a garage or basement floor from the area, the dry film thickness you want and the product’s solids content.

Updated Oct 2, 2026A free tool from homesblogs

What is a epoxy calculator?

Epoxy coatings are specified by dry film thickness in mils (thousandths of an inch). This calculator converts the thickness you want into gallons, allowing for the fact that part of any coating that is not 100% solids evaporates as it cures.

How does it work?

One US gallon spread 1 mil thick covers 1,604 sq ft. Dividing that coverage by your target thickness and adjusting for solids gives coverage per gallon; the tool then multiplies by area and coats and adds waste. Planning the rest of the room? The Flooring Calculator handles tile and plank floors.

What information is needed?

  • Floor area in square feet
  • Target dry film thickness per coat (mils)
  • Solids by volume from the product data sheet
  • Number of coats

How to use the Epoxy Calculator

  1. Measure the floor area.
  2. Check the product data sheet for solids and recommended thickness.
  3. Enter the number of coats — primer and topcoat count separately if they are the same product.
  4. Select Calculate and round up to whole kits.

The formula

In plain terms, here is the calculation the tool runs:

Gallons per coat = Area × Mils ÷ (1,604 × Solids)
Total = Gallons per coat × Coats × (1 + Waste)
1,604
Sq ft one gallon covers at 1 mil
Mils
Dry film thickness per coat
Solids
Solids by volume as a decimal

Worked example

Example

A 400 sq ft garage, two coats of 100% solids epoxy at 10 mils, 10% waste.

  1. 400 × 10 ÷ 1,604 = 2.49 gal per coat
  2. 2.49 × 2 coats = 4.99 gal
  3. 4.99 × 1.10 = 5.49 gal

Buy about 5.5 gallons — four 1.5-gallon kits.

Frequently asked questions

What does solids content mean?

It is the share of the liquid that stays on the floor after curing. A 50% solids product applied 20 mils wet leaves a 10 mil film.

How thick should a garage floor coating be?

A total of 15–25 mils across primer and topcoat is common for residential garages. Heavier traffic warrants more.

Do flakes change the amount?

Flakes do not add much volume, but a clear topcoat over a full flake broadcast needs roughly 20% more material.

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