Free Epoxy Resin Quantity calculator
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Volume estimates assume complete fill to stated dimensions. Actual yield may vary by brand and mixing losses.
Results are estimates. Consult a professional.
How the epoxy resin quantity calculator works
The calculator finds the volume of your pour in cubic inches from the shape dimensions, converts that volume to fluid ounces using the exact US unit relationship (128 fl oz per 231 in³), and then splits the total into Part A and Part B using your chosen mix ratio. Change any input and the result updates instantly.
Epoxy mix ratios: 1:1, 2:1, and 4:1 explained
The mix ratio is the volume proportion of resin (Part A) to hardener (Part B). It is set by the chemistry of the specific product and must be followed exactly — an off-ratio mix will cure sticky, remain soft, or become brittle. Most consumer casting resins are 1:1; laminating and marine epoxies are commonly 2:1 or 4:1.
| Mix ratio | Part A | Part B | Common use |
|---|---|---|---|
| 1:1 | 50% | 50% | Casting, art resin, table tops |
| 2:1 | 67% | 33% | Laminating resin, fiberglass work |
| 4:1 | 80% | 20% | Coating resin, marine epoxy |
A worked example: 12 × 12 inch river table slab
Lisa is filling a 12 in × 12 in void in a river table, 0.25 in deep, using a 1:1 casting resin.
Step 1 — Find the volume
12 × 12 × 0.25 = 36 in³
Step 2 — Convert to fluid ounces
36 × (128/231) ≈ 19.95 fl oz total
Step 3 — Split by mix ratio (1:1)
Part A = 19.95 / 2 ≈ 9.97 fl oz; Part B = 9.97 fl oz
Step 4 — Count cups
ceil(19.95 / 8) = 3 cups (8 fl oz per standard mixing cup)
Rectangular vs. round pours
Most flat pours — river tables, serving boards, art panels, countertop fills — fit the rectangular shape. Round comes into play for coasters, clock faces, lazy Susans, tumblers, and any circular mold. Both shapes need just three measurements: two that define the footprint and a depth for the thickness of the pour.
Rectangular
Multiply length × width × depth. For L-shaped or irregular molds, split the area into rectangles, calculate each separately, and add the volumes together before entering a combined total.
Round
For round molds, enter the full diameter (not the radius). The calculator uses π × r² × depth internally, where r = diameter / 2. A 6-inch diameter coaster at 0.25 in deep yields π × 3² × 0.25 ≈ 7.07 in³.
Tips for accurate epoxy resin pours
- Temperature matters — most epoxies need 70–80°F (21–27°C) to cure; below 65°F, the resin may not harden fully.
- Mix in two stages — for large pours, mix Part A and B in one container, then transfer to a second clean container and mix again. This ensures thorough blending.
- Thin layers for deep pours — casting resins generating heat (exotherm) when curing; pours deeper than 0.5 in should be done in multiple thin layers.
- Surface prep — sand porous wood before pouring; seal with a thin sealer coat to prevent air bubbles from escaping the wood.
- Add 10% waste — mixing losses, drips, and material left in containers consume 5–10% of the calculated amount.
Fluid ounces, milliliters, and cups
Epoxy brands mix US and metric units freely — the bottle may say "32 oz" and the mixing instructions may say "mL." This table pins the exact relationships so you can convert between the units without guessing. The calculator shows all three simultaneously so you can match whichever unit your scale or measuring cups use.
| Unit | Equals |
|---|---|
| 1 fl oz (US) | 29.5735 mL |
| 1 cup (US) | 8 fl oz / 236.6 mL |
| 1 pint | 16 fl oz / 473.2 mL |
| 1 quart | 32 fl oz / 946.4 mL |
How accurate is this epoxy resin calculator?
The geometry is exact. The conversion factor 128/231 is the precise US fluid-ounce per cubic inch — derived from the legal definition of the US gallon (231 in³) and the fluid ounce (1/128 gallon). There is no rounding in the underlying math; the calculator carries full precision and only rounds the display.
Real-world variation comes from mixing losses (5–10%), material left clinging to mixing containers and stir sticks, and surface absorption by porous substrates like wood. The depth you pour also tends to run slightly over the target as you fill. As a rule, always buy 10–15% more than the calculated amount so a single pour fills the mold completely without running out mid-pour.
About the Epoxy Resin Quantity Calculator
This free calculator runs entirely in your browser — no data is sent to any server and no personal information is collected or stored. Results are calculated instantly from the dimensions you enter and are not saved after you leave the page.
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