How much epoxy do I need for a garage floor?

It depends on the coating thickness, but most floor-coating epoxies are applied around 0.5-2 mm thick. For a typical single-car garage floor of roughly 15-18 m² (around 160-190 sq ft) at 1 mm thick, that works out to roughly 15-20 litres of mixed epoxy including a waste allowance — always confirm the exact coverage rate on your chosen product's data sheet, since formulations vary.

What mix ratio should I use for epoxy resin?

Whatever ratio the manufacturer's data sheet specifies for your exact product — common ratios are 1:1, 2:1, or 3:1 (resin:hardener) by volume, and mixing at any other ratio than what that specific product was formulated for can leave it permanently soft or tacky. This calculator offers 1:1 through 4:1 presets purely to split your total volume once you know your product's correct ratio; it does not determine the ratio for you.

Why can't I pour epoxy resin thicker than about 1/4 inch (6mm) in one go?

Epoxy cures through an exothermic chemical reaction — it releases heat as it hardens. A thin layer sheds that heat quickly into the air, but a deep pour traps it, and the resin can overheat, yellow, crack, or in extreme cases smoke as it cures. That's why most casting epoxies cap a single pour at around 6mm (1/4in) and recommend building up thicker pieces, like river tables or bar tops, in several separate "flood coats" instead.

Can I apply epoxy flooring in an unheated Canadian garage in winter?

Most epoxies need the slab and ambient air within a specific temperature range (often 10-25°C) to cure properly, so an unheated garage in a Canadian winter is usually too cold — the resin can stay soft, cure unevenly, or fail to bond to a cold concrete slab. Either heat the space to the product's minimum cure temperature or wait for warmer weather.

Does an unheated concrete slab need extra prep before epoxy coating in Canada?

Yes — concrete slabs exposed to Canadian freeze-thaw cycles are more likely to have surface moisture or minor cracking that needs addressing before coating. A moisture test (and, if needed, a moisture-mitigating primer) is worth the extra step, since trapped moisture under an epoxy coating is a common cause of bubbling or delamination.

Epoxy Calculator — Resin & Hardener Needed

How Much Epoxy Resin Do I Need?

Epoxy is unforgiving in a way paint isn't: run short partway through a pour and you can't just nip back for another tin and carry on, because the batch you mixed has already started to cure. Working out the right quantity before you crack open a single pump is the difference between a smooth, level finish and a visible "witness line" where an old pour meets a new one. This calculator works from three numbers — the surface's length and width (or diameter, for a circular pour), and the coating thickness you're applying — to give you a volume of mixed epoxy, split into the exact amount of resin and hardener your mix ratio needs.

The same formula covers two very different jobs. Coating a garage, basement, or workshop floor typically means a thin layer, often well under a millimetre to a couple of millimetres per coat, rolled or squeegeed across a large area. Casting a bar top, river table, or tabletop usually means a much thicker single pour — sometimes a centimetre or more — over a smaller area. Both are just area multiplied by thickness; the calculator handles either shape (rectangular or circular) and any thickness you enter, and flags when your thickness has crossed the standard single-pour depth limit so you know to plan multiple thinner "flood coats" instead of one deep pour.

How to Use the Epoxy Calculator

Choose your surface shape: rectangular (for a floor, tabletop, or countertop) or circular (for a round table or disc mould).
Enter the coating thickness you plan to apply, in metres — for a thin floor coat this might be 0.001-0.002 m (1-2 mm); for a tabletop pour it could be 0.006-0.02 m (6-20 mm).
For a rectangular surface, enter its length and width. For a circular surface, enter its diameter.
Pick a resin:hardener mix ratio preset (1:1, 2:1, 3:1, or 4:1) matching the product you're using — check the manufacturer's data sheet, since mixing an epoxy at the wrong ratio can leave it soft, tacky, or unable to cure at all.
Set a waste allowance to cover mixing-cup residue, roller/brush loss, and any spillage — 10% is a sensible default, more if it's your first time working with resin.
Read off the surface area, the total mixed-epoxy volume, and the separate resin and hardener volumes to measure out, plus the estimated cost.
If the calculator flags that your thickness exceeds the standard single-pour depth limit, plan for multiple flood coats rather than one deep pour — see the tips below for why.

The Formula Behind the Numbers

The calculation runs in three stages. First, find the surface area: length x width for a rectangular surface, or pi x radius^2 for a circular one (radius is half the diameter you entered). Second, multiply that area by the coating thickness to get the raw volume of mixed epoxy needed. Third, add your waste percentage on top, then split the total into resin and hardener according to your chosen mix ratio — for a 2:1 ratio, two-thirds of the volume is resin and one-third is hardener; for a 1:1 ratio, it's an even half each.

Worked example: a garage floor section 4 m long and 3 m wide, coated 1 mm (0.001 m) thick, mixed at a 2:1 resin:hardener ratio with a 10% waste allowance.

Surface area: 4 x 3 = 12 m². Raw volume: 12 x 0.001 = 0.012 m³, which is 12 litres (1 m³ = 1,000 litres). With 10% waste: 12 x 1.10 = 13.2 litres of mixed epoxy needed. Splitting by the 2:1 ratio (2 + 1 = 3 total parts): resin = 13.2 x (2/3) = 8.8 litres, hardener = 13.2 x (1/3) = 4.4 litres.

That 1 mm thickness is nowhere near the standard single-pour depth limit of roughly 6 mm (1/4 in), so this whole 13.2 litres can go down as a single coat. If the same floor needed a 10 mm decorative pour instead, the calculator would flag it as exceeding that limit and you'd plan two or three thinner flood coats rather than one deep one.

Pro Tips and Common Mistakes

Surface preparation matters more than which epoxy brand you buy. Epoxy bonds to whatever is on the surface, not what's underneath it — grease, dust, old sealer, or moisture trapped in concrete will all telegraph through as bubbles, fish-eyes, or a coating that peels within months. A ground or acid-etched, thoroughly degreased, bone-dry surface is what actually determines whether a floor coating lasts years or fails in one winter.

Epoxy resin in Canada is typically sold by the litre, with price scaling directly with brand, formulation, and whether it's rated for cold-weather curing. For example, a 4 m x 3 m floor coated 1 mm thick needs 13.2 litres of mixed epoxy after a 10% waste allowance (8.8 litres of resin and 4.4 litres of hardener at a 2:1 ratio) — at CAD 58/litre, that works out to roughly CAD 765.60 in material for the whole job. Scale that same per-litre price by your own calculated volume above to budget a different job, and check the data sheet's minimum cure temperature if the space isn't heated year-round.

Measure resin and hardener by volume (or weight, if the data sheet specifies it) as precisely as you can — epoxy cures through a chemical reaction between the two parts, not by evaporation like paint, so an off-ratio mix can stay soft and tacky indefinitely, and no amount of extra drying time fixes that.
Respect the single-pour depth limit (around 6 mm / 1/4 in for most casting epoxies). Epoxy cures exothermically — it generates its own heat — and a pour that's too deep can overheat, discolour, crack, or even smoke as it cures. Thick tabletop or river-table pours are built up in multiple thinner "flood coats" instead, each allowed to gel before the next goes on.
A second, thin "flood coat" over a cured base coat fills in pinholes, brush marks, and dust nibs for a glass-like final surface — budget for it separately from your main coat.
Cure time is not the same as recoat time. Most epoxies are touch-dry within 24 hours but need several days (often 5-7) to reach full chemical cure — keep heavy foot traffic and furniture off a new floor coating until then.
Buy slightly more than the calculator says, especially for a first pour — running out mid-mix on a large tabletop or floor bay is far harder to recover from than having a little leftover mixed epoxy for touch-ups.