How it works
The calculator takes the floor area, multiplies it by the number of coats, adds any extra and divides by the area one kit covers.
Floor area = Length × Width
Kits = ⌈ Floor area × Coats × (1 + Extra ÷ 100) ÷ Coverage per kit ⌉
Topcoat kits = ⌈ Floor area × Topcoat coats × (1 + Extra ÷ 100) ÷ Topcoat coverage per kit ⌉
Flake bags = ⌈ Floor area × (1 + Extra ÷ 100) ÷ Flake coverage per bag ⌉
⌈ ⌉ means rounding up: a two-part kit is mixed whole, so you buy whole kits. The area and the coverage are converted to the same unit first, so you can measure in feet and read a label in square metres.
Worked example in words
A 20 × 12 ft garage floor is 240 sq ft. Rust-Oleum’s EpoxyShield 1 Car Kit label says one kit covers up to 200–250 sq ft in one coat; with the low end, 240 ÷ 200 = 1.2 kits, so you buy two. With the QUIKRETE kit at 220 sq ft the result is the same – 1.09, so two kits – and a QUIKRETE High Gloss topcoat at 500 sq ft per kit adds one topcoat kit.
Where the coverage comes from
Each kit in the list uses the figure its maker publishes. The Rust-Oleum EpoxyShield 1 Car Kit label gives “up to 200–250 sq ft” and one coat; QUIKRETE’s 2-Part Epoxy Kit data sheet gives 220–280 sq ft (20–26 m²) per 120 fl oz kit depending on surface porosity; Rust-Oleum Europe’s data sheet gives about 25 m² of smooth bare concrete and 12–20 m² on very rough or porous concrete. The calculator uses the low end of each range, and for the European kit you choose smooth (25 m²) or rough (12 m²). If your kit isn’t listed, choose “Your own coverage” and type the figure from its label.
Topcoat and flakes
QUIKRETE’s Epoxy High Gloss Coating covers up to 500 sq ft (46 m²) of coated concrete per kit – twice what it covers on bare concrete – which is the figure used when you pick it as a topcoat over the epoxy. Decorative flakes for a light sprinkle come with the listed kits. For a full broadcast or extra flakes, enter the area one bag covers from the flake product’s label and the calculator counts bags.
Surface preparation decides how far a kit goes and how well it lasts: follow your kit’s instructions for cleaning, etching or grinding, moisture testing and cure time. Coverage depends on the concrete’s texture and porosity, so buy the last kit once you see how far the first one goes.
Worked example
Inputs
- Measure by
- Floor length × width
- Floor length
- 20 ft
- Floor width
- 12 ft
- Number of coats
- 1
- Epoxy kit
- Rust-Oleum EpoxyShield Garage Floor Coating, 1 Car Kit – 200 sq ft (≈ 18.6 m²) per kit
- Extra
- 0 %
- Clear topcoat
- No topcoat
Result
- Floor area
- 240 sq ft
- Coverage per kit used
- 200 sq ft
- Epoxy kits
- 2
Common mistakes
- Using the largest coverage figure on the box. Labels often give a range such as 200–250 sq ft; on a real garage floor the low end is the safer number.
- Ignoring porosity. Old, rough or freshly etched concrete absorbs more coating than smooth concrete, and a kit then covers noticeably less.
- Mixing more than you can roll out. Two-part epoxy has a limited pot life once mixed – Rust-Oleum Europe gives 3 hours – so plan the floor in sections and mix kit by kit.
- Forgetting the topcoat in the budget. A clear topcoat has its own coverage, often different from the base coat over bare concrete.
- Coating new concrete too early. QUIKRETE says concrete and repairs must cure 30 days before its epoxy is applied.
Assumptions and limits
- The floor is a rectangle of length × width, or the area you enter.
- Coverage is the documented area per kit for one coat – the low end of the range on the label or data sheet, or the rough-concrete figure where one is given – or the figure you type. It applies to every coat.
- Kits are rounded up to whole kits; parts of a kit are not mixed separately.
- The topcoat coverage is per kit over a coated floor. Flakes are counted only if you enter the coverage per bag.
- Walls, stairs and curbs are not included. Add their area to a known area if you coat them.
Frequently asked questions
How many epoxy kits do I need for a two-car garage?
Measure the floor and divide by the kit coverage. QUIKRETE uses 420 sq ft as a typical two-car garage; at the 200 sq ft per kit on Rust-Oleum’s 1 Car Kit label that is 420 ÷ 200 = 2.1, so three kits for one coat.
How much area does one epoxy kit cover?
It depends on the product and the concrete. Rust-Oleum’s EpoxyShield 1 Car Kit label says up to 200–250 sq ft, QUIKRETE’s 2-Part Epoxy Kit data sheet says 220–280 sq ft, and Rust-Oleum Europe says about 25 m² on smooth bare concrete and 12–20 m² on rough or porous concrete.
Do I need two coats of epoxy?
Follow the kit label. Rust-Oleum’s 1 Car Kit label says one coat. If you plan two, set the number of coats to 2 and the calculator doubles the coating.
How much topcoat do I need?
Divide the floor area by the topcoat’s coverage. QUIKRETE’s Epoxy High Gloss Coating covers up to 500 sq ft of coated concrete per kit, so a 240 sq ft garage takes one kit.
Are flakes included in the kit?
Many garage kits include flakes for a light sprinkle – the Rust-Oleum and QUIKRETE kits listed here both do. For a heavier or full broadcast, enter the coverage per bag of the flakes you buy.
Sources
- EpoxyShield Garage Floor Coating 1 Car Kit (Tint Base) – product label — Rust-Oleum. 1 Car Kit (120 fl oz) covers up to 200–250 sq ft in one coat; decorative chips included (preset uses 200).
- Epoxyshield Garage Floor Coating – Technical Data Sheet — Rust-Oleum Europe. One kit covers about 25 m² of smooth bare concrete and 12–20 m² of very rough or porous concrete (rough preset uses 12); pot life 3 hours.
- 2-Part Epoxy Kit Garage Floor Coating No. 0703-57, -58 – Data Sheet — The QUIKRETE Companies. One 120 fl oz (3.55 L) kit covers a one-car garage, 220–280 sq ft (20–26 m²) depending on porosity; color flakes included (preset uses 220).
- 2-Part Epoxy Kit Epoxy High Gloss Coating No. 0703-55 – Data Sheet — The QUIKRETE Companies. One 120 fl oz (3.55 L) kit covers up to 500 sq ft (46 m²) of coated concrete and 250 sq ft (23 m²) of uncoated concrete (topcoat preset uses 500).
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 4, 2026