Epoxy Resin Calculator
GroundworkMeasurements in, purchasing amount out
How the Epoxy Resin Calculator works
This tool counts units of a product rather than cubic yards, so the answer depends on the piece size you actually buy. Change the selection and the figure changes with it. The suggested order adds the waste allowance shown beside it, as its own number rather than a multiplier you have to apply.
Using your measurements
48 in × 30 in × 0.125 in = 99.7 fl oz
Assumption: 0.125 in flood coat · 1:1 by volume · 1 gal kits · 10% extra
Same job, next question
What else this job needs
The full breakdown
How much epoxy you need — for a table top, a river table, or a garage floor
The epoxy resin calculator above answers one question for three very different jobs: how much resin to buy. A table top or bar top flood coat is a thin layer over a flat surface; a deep pour or river table is a mould filled in thick layers; a garage floor is rolled on by coverage rate, coat by coat. Pick the job, enter what you measured, and the readout gives the mixed volume in gallons, fluid ounces and litres, the number of kits, the part A and part B amounts for your mix ratio, and — for a deep pour — how many layers it takes and how long to wait between them.
Every answer rests on one fact: a US gallon is exactly 231 cubic inches. A table top 48 × 24 in coated ⅛ in deep holds 1,152 × 0.125 = 144 in³ of resin, and 144 ÷ 231 is 0.62 gallons, or about 80 fluid ounces. In metric it is simpler still: one square metre at one millimetre is exactly one litre, so a 3 mm flood coat takes 3 L per m².
Deep pours add a second limit, which is heat. Epoxy cures by an exothermic reaction, and the thicker the layer the less of that heat can escape. A coating resin that is perfect at ⅛ in can crack, yellow or smoke at an inch. That is why the calculator asks what type of resin you are using, divides the pour depth by that resin’s maximum layer, and tells you how many pours the job really is — and roughly how many days it adds up to.
Floors are bought the other way round: the can tells you how many square feet a gallon covers, not how thick it goes on. The two are the same fact said twice. One gallon spread over one square foot is 1,604 mils (thousandths of an inch) thick, so coverage in ft²/gal is simply 1,604 divided by the wet film thickness in mils — 160 ft²/gal is a 10 mil coat. For heavier concrete work around the floor, the concrete calculator sizes the slab itself.
Worked examples and quick figures
Each line is the same arithmetic the calculator runs. Volumes are before the extra allowance; add 10% for what stays in the cup, on the sticks, and on the floor.
| Epoxy | Worked examples and quick figures |
|---|---|
| Flood coat, per square foot | ⅛ in deep = 18 in³ = 9.97 fl oz per ft² · 1 gal covers 12.8 ft² at ⅛ in, 25.7 ft² at ¹⁄₁₆ in |
| Flood coat, per square metre | 1 mm deep = 1 L per m² · a 3 mm coat takes 3 L per m² |
| Table top 48 × 24 in at ⅛ in | 144 in³ = 0.62 gal = 80 fl oz · with 10%, 88 fl oz — one 1 gal kit |
| Dining table 72 × 36 in at ⅛ in | 324 in³ = 1.40 gal · with 10%, 1.54 gal — two 1 gal kits, or one 2 gal kit |
| River table 72 × 20 in, 2 in deep, 60% resin | 1,728 in³ = 7.48 gal (exactly 1 ft³) · 1 pour of deep-pour resin, 4 pours at ½ in · with 10%, three 3 gal kits |
| Garage 20 × 20 ft, 2 coats at 160 ft²/gal | 400 ÷ 160 × 2 = 5 gal · with 10%, 5.5 gal — two 3 gal kits |
| Two-car garage 24 × 24 ft, 2 coats at 160 ft²/gal | 576 ÷ 160 × 2 = 7.2 gal · with 10%, 7.9 gal |
| Coverage and film thickness | 1,604 ÷ mils = ft²/gal · 5 mil = 321, 10 mil = 160, 16 mil = 100, 20 mil = 80 ft²/gal |
| A 3 gal kit at 2 : 1 by volume | 2 gal of part A + 1 gal of part B · a 1 gal kit at 1 : 1 is 64 fl oz of each |
A pour, in the order the steps actually happen
Most epoxy failures are preparation and timing failures, not quantity failures. The steps below cover the two common jobs; skip the ones that do not apply to yours.
Measure and buy Before anything else | Measure the mould or the floor, run the calculator, and buy the kits plus the extra. Check the data sheet for the maximum pour depth and the recoat window — they set the schedule. |
|---|---|
Seal the wood or prime the floor Day 1 | Brush a thin seal coat on raw wood so air in the grain does not bubble up through the flood coat. On concrete, grind or etch, vacuum, and roll a primer coat. |
Build and level the mould Day 1 | For a deep pour, line a melamine or HDPE form with sheathing tape, caulk every seam, and level it both ways. A mould that is out of level is a pour that is thicker at one end. |
Mix Pour day | Measure A and B exactly — by volume in graduated cups, or by weight on a scale, as the product says. Stir slowly for the full time on the label, scraping the sides and bottom, then pour into a second container and stir again. |
Pour a layer Pour day | Pour no deeper than the product allows. Spread a flood coat with a notched spreader and let it self-level; pop surface bubbles with a heat gun or torch held moving. |
Wait, then pour again Hours to days | Wait the recoat window between layers. Inside it the next pour bonds chemically; after it, sand the surface before the next layer so it has something to grip. |
Cure 3 to 14 days | Keep the room at the rated temperature and the dust off. A surface that is hard to the touch is not fully cured; do not demould, sand or load it until the data sheet says so. |
Finish After full cure | Demould, flatten and sand through the grits, then polish or apply a final flood coat. On a floor, roll the topcoat inside its recoat window. |
Kit sizes and mix ratios
Epoxy kits are sold by the mixed volume of resin and hardener together. A 1 gal kit of a 1 : 1 product is half a gallon of each; a 1.5 gal kit of a 2 : 1 product is a gallon of resin and half a gallon of hardener. The ratio printed on the bottle is the one to follow, and it says whether it is by volume or by weight — 2 : 1 by volume and 2 : 1 by weight are not the same mix, because resin is denser than hardener. Mixing a little more of one part does not make the epoxy cure harder; it leaves unreacted resin or hardener that stays soft or tacky.
Mix only what you can pour inside the product’s working time. A large batch left in the bucket cures faster than the same resin poured out thin, and a full 3 gal bucket can overheat while you are still spreading it.
What goes wrong with epoxy pours
Pouring deeper than the resin allows
A coating resin poured an inch deep traps its own heat. The result can be cracking, yellowing, a wavy surface, or a mould that warps. Pour in layers no thicker than the data sheet allows, or use a resin made for deep pours.
Running short mid-pour
A flood coat that runs out halfway across the table leaves a line that will not sand out. Buy the extra, and mix the whole coat before you start pouring rather than chasing it with a second batch.
Mixing by guesswork
Off-ratio epoxy stays soft, sticky or cloudy. Use graduated cups for a ratio by volume and a scale for a ratio by weight, and never convert one to the other without the densities from the data sheet.
Bubbles from the wood
Air leaves raw wood as the resin warms it and rises through the coat. A thin seal coat first, allowed to cure, stops most of it.
Leaks in the mould
Resin finds every gap. A river table mould that leaks overnight leaves a low spot and a puddle on the floor. Tape, caulk, and test the seams before the pour.
Skipping floor preparation
Epoxy on a dusty, oily or sealed slab peels under hot tyres. Grind or etch the concrete, test for moisture, and prime. Most floor coating failures trace back to preparation, not to the product.
Frequently Asked Questions
Epoxy quantities, pour depths, kits and mix ratios
How do I calculate how much epoxy I need?
Multiply length × width × thickness in inches to get cubic inches, then divide by 231 for US gallons, or multiply by 0.554 for fluid ounces. In metric, length × width in metres × thickness in millimetres gives litres directly. Add about 10% for what stays in the cup and runs off the edges, then divide by the kit size and round up.
How much epoxy do I need for a table top?
At the usual ⅛ in flood coat, about 10 fl oz per square foot — one gallon covers about 12.8 ft². A 48 × 24 in top takes about 80 fl oz, so a 1 gal kit with some to spare; a 72 × 36 in dining table takes 1.4 gal, so two 1 gal kits or one 2 gal kit.
How much epoxy do I need for a river table?
Multiply the length, width and depth of the mould in inches, multiply by the share of the mould that is resin rather than wood, and divide by 231 for gallons. A 72 × 20 in river 2 in deep with the slabs taking 40% of the box is 1,728 in³ — 7.5 gallons, or 8.2 with the extra.
How deep can I pour epoxy in one layer?
It depends on the resin. Table top and coating epoxies are usually limited to about ⅛ to ¼ in (3–6 mm) a pour; medium-pour resins to about ½ in (12 mm); deep-pour casting resins to about 2 in (50 mm); and a few extra-deep products to 3 in (75 mm) or more in small castings. The product’s data sheet is the limit that counts.
How long should I wait between epoxy pours?
A coating resin can usually be recoated in about 4 to 12 hours, while a deep-pour resin often needs 24 to 72 hours before the next layer. Pour inside the recoat window and the layers bond chemically; miss it and you need to sand the surface first.
How much epoxy do I need for a garage floor?
Divide the floor area by the coverage on the label and multiply by the number of coats. A two-car garage of 24 × 24 ft is 576 ft²; at 160 ft²/gal and two coats that is 7.2 gallons, or about 7.9 with 10% extra. At the same rate, 400 ft² takes 5 gallons and 1,000 ft² takes 12.5 gallons before the extra.
How many square feet does a gallon of floor epoxy cover?
For a 100% solids epoxy, 1,604 ÷ the wet film thickness in mils. At 10 mils that is 160 ft²; at 16 mils it is 100 ft². Water-based garage kits go on thinner and cover more per gallon, but leave a thinner film once the water evaporates — use the coverage figure on the product label.
What does 1 : 1 or 2 : 1 mean on epoxy?
It is the ratio of part A (resin) to part B (hardener). A 1 : 1 product mixes equal amounts; a 2 : 1 product mixes two parts resin to one part hardener. The calculator splits your total into the two amounts for whichever ratio you choose.
Should I mix epoxy by weight or by volume?
By whichever the manufacturer specifies. A ratio by volume is measured in graduated cups; a ratio by weight on a scale. They are different numbers for the same product, because resin and hardener have different densities, so a 2 : 1 by volume mix is not 2 : 1 by weight.
How much epoxy do I need per square foot?
About 10 fl oz per square foot at ⅛ in, 5 fl oz at ¹⁄₁₆ in, and 20 fl oz at ¼ in. Each extra ⅛ in of thickness adds another 10 fl oz per square foot. In metric, each millimetre of thickness takes 1 L per square metre.
How much epoxy do I need for a round table?
Work out the area as π × radius², then multiply by the thickness. A 36 in round top is 3.1416 × 18 × 18 = 1,018 in²; at ⅛ in that is 127 in³ — 0.55 gal, or about 70 fl oz. To use the calculator, enter a square of the same area: length and width both 0.886 × the diameter, so 31.9 in for a 36 in circle.
How do I convert epoxy to millilitres or grams?
One fluid ounce is 29.6 mL and one litre is 1,000 mL. For grams, multiply millilitres by the mixed density, about 1.05 to 1.15 g/mL — so the 80 fl oz table top above is 2,370 mL, or roughly 2.5 to 2.7 kg of mixed resin. A product sold by weight lists its exact density on the data sheet.
How much does a gallon of epoxy weigh?
Mixed epoxy is about 8.8 to 9.6 lb per gallon (1.05–1.15 kg per litre), a little heavier than water. The resin part is usually denser than the hardener — one table top product lists 9.7 lb/gal for resin and 8.1 lb/gal for hardener.
How much extra epoxy should I buy?
About 10% for an ordinary job: resin left in the cup and on the stir sticks, and drips over the edges. Go to 15–20% for raw, open-grained wood, porous concrete, or a top whose edges are flooded rather than taped.
What happens if I pour epoxy too thick?
The heat of curing has nowhere to go. A thick pour of a fast resin can crack, turn yellow, ripple, release fumes, or soften and warp a plastic mould. Pour in layers no thicker than the product allows.
How long does epoxy take to fully cure?
Most coating resins are hard in a day and fully cured in 3 to 7 days. Deep-pour resins can take 5 to 10 days after the last layer, and extra-deep casting resins two weeks. A cold room can double those times.
Is this calculator for anchoring epoxy?
No. Epoxy anchoring adhesive for rebar and bolts — the products Hilti and Simpson Strong-Tie publish their own estimators for — is sized from hole diameter, embedment depth and the manufacturer’s cartridge tables. This calculator is for coating and casting resin only.