Epoxy Resin Calculator
Epoxy is one of the most expensive materials you will buy for a project, and the classic mistake is buying a kit that is one size too small — then discovering mid-pour that a second pour will leave a visible seam. This calculator works out the exact fluid ounces of mixed resin your surface needs from your dimensions and pour thickness, splits it into part A and part B by your mix ratio, and tells you exactly how many kits to buy and what they will cost.
Your Resin Project
The Epoxy Volume Formula
Epoxy is sold by volume, and the volume you need is pure geometry:
Volume (fl oz) = (Length_in × Width_in × Pour_Thickness_in) ÷ 1.8047
One cubic inch holds 1.8047 fluid ounces, so divide the cubic-inch volume by that constant to get ounces. A 6 × 2 foot table coated at 1/8 inch is 72 × 24 × 0.125 = 216 cubic inches, which equals about 120 fl oz before the waste allowance — almost exactly one gallon of mixed resin.
Pour Thickness by Project
Choosing the right pour thickness is as important as the volume math, because epoxy is self-limiting: a single pour thicker than the manufacturer's maximum (often 1/8 inch to 1/2 inch) traps heat and can crack or bubble. Deep pour and river table resins have longer cure times and special formulations designed for 1/2 inch and beyond.
- Flood / seal coat (1/16 inch): a thin protective layer over wood or stone countertops.
- Tabletop coat (1/8 inch): the standard glossy finish for furniture and bars.
- Casting (1/4 inch): jewelry, small molds, and embedded objects.
- Deep pour (1/2 inch+): river tables and thick slabs; requires a deep-pour formula and often multiple staged pours.
If your project thickness exceeds the manufacturer's single-pour maximum, split it into staged pours — and remember to add the waste allowance to the total, because every staging step loses a little more resin to mixing cups and cleanup.
Worked Example: Coating a 6×2 Foot Bar Top
A 6 × 2 foot bar top at a 1/8-inch tabletop coat, one coat, 1:1 mix, with 10% waste: surface is 72 × 24 = 1,728 square inches; volume is 1,728 × 0.125 = 216 cubic inches = about 119.7 fl oz. Add 10% waste for 131.7 fl oz, so you need 132 fl oz of mixed resin — one 128 oz (gallon) kit is just short, so buy a gallon plus a 16 oz kit. At $55 for the gallon and $10 for the small kit, the project costs about $65 and leaves you a small buffer for touch-ups.
Real-World Case Study: Epoxy River Table Build
A woodworker built a 6 × 3 ft walnut river table with a 1.5-inch-deep epoxy pour. The river channel averaged 8 inches wide × 72 inches long. Volume = 8 × 72 × 1.5 = 864 cubic inches ≈ 475 fl oz (3.7 gallons). With 15% waste (mixed resin in cups, drips, bubbles), total needed was 546 fl oz ≈ 4.3 gallons. Using 2:1 deep-pour epoxy at $45/gallon, the resin cost was $193. The pour took two stages (manufacturer max single-pour: 1 inch) with 24 hours between stages. The final table sold for $2,400 — resin was only 8% of the total material cost.
Key takeaway: For deep pours, always split into stages within the manufacturer's single-pour max. Buying the right amount upfront avoids the costly mistake of a mid-pour color mismatch from a different batch.
Epoxy Coverage Comparison by Pour Type
The amount of epoxy needed per square foot varies dramatically with pour thickness. This table helps you estimate coverage for common project types.
| Pour Type | Thickness | Fl oz per sq ft | Gallons per 20 sq ft | Typical Project |
|---|---|---|---|---|
| Flood / seal coat | 1/16 in | 1.0 | 0.16 | Countertop seal |
| Tabletop coat | 1/8 in | 2.0 | 0.31 | Bar top, furniture |
| Casting | 1/4 in | 4.0 | 0.62 | Jewelry, coasters |
| Deep pour | 1 in | 16.0 | 2.50 | River table, slab |
| Deep pour | 2 in | 32.0 | 5.00 | Thick river table |
Cost tip: Flood coats are cheap ($2–5 per sq ft in material), while deep pours at 2 inches cost $15–30 per sq ft. Plan your thickness carefully — every extra 1/8 inch on a 30 sq ft table adds $10–20 in resin.
Frequently Asked Questions
How much epoxy do I need for a tabletop?
A 6×2 foot table at 1/8-inch thickness needs about 120 fl oz before waste — roughly one gallon of mixed resin. Use the calculator with your exact dimensions and pour thickness.
How many square feet does a gallon of epoxy cover?
About 12 sq ft at 1/8 inch, 6 sq ft at 1/4 inch, and 1.5 sq ft at a 1/2-inch deep pour. Coverage is exactly area × thickness, so thinner coats always go further.
What if I use a 2:1 epoxy?
You simply mix two parts resin to one part hardener by volume. The calculator splits your total into part A and part B automatically — just match the product label exactly.
Why should I buy extra?
Resin sticks to cups and brushes, bubbles escape during curing, and spills happen. A 10–15% buffer prevents the worst-case: running short mid-pour and seeing a visible line from a second pour.
Can I pour a thick river table in one go?
Only with a deep-pour formulation within its rated depth, usually 1/2 inch to 2 inches. Thicker pours generate exothermic heat that can crack the resin, so stage thick pours in layers.