hobby calculator

Epoxy Resin Mixing Calculator

Calculate exact resin and hardener volume and weight for tabletop pours, coasters, and river tables from your mold dimensions and mix ratio.

Fill volume (in³) = length × width × thickness, converted to fluid ounces at 0.554 oz per in³, then split by mix ratio. A 24" × 12" panel poured 1/8" deep needs about 22 fl oz of mixed epoxy at a 1:1 ratio — roughly 11 fl oz of resin and 11 fl oz of hardener, before a waste allowance.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Lengthin

Widthin

Pour thicknessin

Waste allowance%

Mix ratio — resin parts

Mix ratio — hardener parts

Resin densityg/mL

Hardener densityg/mL

Always check your specific product's technical data sheet for the exact mix ratio and densities — these vary by brand and formulation, and an incorrect ratio can leave a soft, tacky, or cloudy cure.

Results

Total mixed volume

21.94 fl oz

Resin (Part A)10.97 fl oz / 373.1 g

Hardener (Part B)10.97 fl oz / 314.7 g

Total weight687.9 g

Weight ratio (resin:hardener)1.19 : 1

Bookmark this epoxy calculator

Different molds, different thicknesses, different products — re-run this per pour rather than reusing an old batch size.

Formula

Epoxy resin mixing formula

Fill volume (in³) = Length × Width × Thickness × (1 + Waste%). Total (fl oz) = Volume (in³) × 0.554. Resin = Total × RatioA ÷ (RatioA + RatioB); Hardener = Total × RatioB ÷ (RatioA + RatioB). Weight (g) = Volume (fl oz) × 29.5735 × Density (g/mL).

Mixing by volume and mixing by weight give different splits whenever resin and hardener have different densities — this calculator shows both so you can measure with a scale or with graduated cups.

Step by step

How the calculation works

1Enter the length, width and pour thickness of your project in inches.
2Add a waste allowance for mixing cup residue and stir-stick loss.
3Enter your product's mix ratio (check the datasheet — common ratios are 1:1 and 2:1 by volume).
4Enter resin and hardener densities if you want an accurate weight split, or use the defaults for a typical tabletop epoxy system.

Example

Worked example — 24" × 12" panel, 1/8" thick, 1:1 ratio

Raw volume = 24 × 12 × 0.125 = 36 in³. With 10% waste: 39.6 in³ = 21.94 fl oz. At a 1:1 ratio: 10.97 fl oz of each. By weight, using densities of 1.15 g/mL (resin) and 0.97 g/mL (hardener): 373.1 g resin and 314.7 g hardener — a 1.19:1 weight ratio despite the 1:1 volume ratio.

Related guides

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Guide

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hobby calculator

Epoxy Resin Mixing Calculator

Calculate exact resin and hardener volume and weight for tabletop pours, coasters, and river tables from your mold dimensions and mix ratio.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Lengthin

Widthin

Pour thicknessin

Waste allowance%

Mix ratio — resin parts

Mix ratio — hardener parts

Resin densityg/mL

Hardener densityg/mL

Results

Total mixed volume

21.94 fl oz

Resin (Part A)10.97 fl oz / 373.1 g

Hardener (Part B)10.97 fl oz / 314.7 g

Total weight687.9 g

Weight ratio (resin:hardener)1.19 : 1

Bookmark this epoxy calculator

Different molds, different thicknesses, different products — re-run this per pour rather than reusing an old batch size.

Summary

Key output metrics

Resin needed

10.97 fl oz

373.1 g by weight.

Hardener needed

10.97 fl oz

314.7 g by weight.

Total mixed volume

21.94 fl oz

Includes a 10% waste allowance over the raw 36.0 in³ fill volume.

True weight ratio

1.19 : 1

Your 1:1 volume ratio, converted using the densities you entered.

D3 visualization

Resin vs. hardener by weight

Even at a 1:1 volume ratio, the weight split usually is not 50/50, because resin and hardener rarely share the same density.

Resin373.1 g

Hardener314.7 g

D3 visualization

Volume needed at different pour thicknesses

How the total mixed volume scales with pour depth for the same length and width.

Guide

How to understand and use this calculator

Quick Answer — How Much Epoxy Do I Need?

The core formula: Fill volume (in³) = Length × Width × Thickness. Add a waste allowance, then convert to fluid ounces: Total (fl oz) = Volume (in³) × 0.554.

Split by ratio: Resin (fl oz) = Total × RatioA ÷ (RatioA + RatioB); Hardener (fl oz) = Total × RatioB ÷ (RatioA + RatioB).

Quick reference:

24" × 12" panel, 1/8" thick, 1:1 ratio, 10% waste → 21.94 fl oz total = 10.97 fl oz each
4" × 4" coaster, 1/4" thick, 2:1 ratio, 5% waste → 2.33 fl oz total = 1.55 fl oz resin, 0.78 fl oz hardener
60" × 20" river table, 1/2" thick, 1:1 ratio, 10% waste → 365.71 fl oz total = 182.86 fl oz each

Worked example: a 24" × 12" panel poured 1/8" deep needs 24 × 12 × 0.125 = 36 in³ of resin. Adding 10% for mixing-cup residue and stir-stick loss: 39.6 in³ = 21.94 fl oz. At a 1:1 ratio, that's 10.97 fl oz of resin and 10.97 fl oz of hardener.

How to Use This Calculator

Enter the length, width and pour thickness of your project in inches — for an irregular mold, measure or estimate its bounding rectangle and thickness, or calculate the true volume with water displacement first for something oddly shaped.

Add a waste allowance — 5-10% is typical, covering the resin left behind on the mixing cup wall, the stir stick, and small drips.

Enter your product's mix ratio from its technical data sheet — common ratios are 1:1 and 2:1 by volume, though some industrial and casting formulations use very different ratios like 100:44 by weight.

Example input: Length = 24 in • Width = 12 in • Thickness = 0.125 in • Waste = 10% • Ratio = 1:1.

Output: Total = 21.94 fl oz • Resin = 10.97 fl oz (373.1 g) • Hardener = 10.97 fl oz (314.7 g).

If you're building a wood-and-resin piece like a river table, size the lumber first with the woodworking board foot calculator, since the wood's final dimensions determine how much resin the void actually needs.

The Formula This Calculator Uses

Every step here is visible arithmetic, not a hidden lookup table.

Fill volume: Length × Width × Thickness, all in inches, gives cubic inches. Adding a waste percentage on top accounts for resin that never makes it into the mold.

Volume to fluid ounces: 1 cubic inch = 0.554113 US fluid ounces.

Splitting by ratio: a 1:1 ratio splits the total evenly; a 2:1 ratio gives the first component (resin) twice the volume of the second (hardener). Total parts = RatioA + RatioB, and each component's share is its own ratio number divided by that total.

Volume to weight: Weight (g) = Volume (fl oz) × 29.5735 (mL per fl oz) × Density (g/mL). Resin and hardener typically have different densities — many two-part epoxy systems run roughly 1.10-1.18 g/mL for the resin (Part A) and 0.92-1.00 g/mL for the hardener (Part B), though this varies by product and you should use your own datasheet's figures when available.

Why the weight ratio can differ from the volume ratio: if resin and hardener have different densities, mixing equal volumes does not produce equal weights. This calculator shows both figures so you can measure with graduated cups (volume) or a kitchen/postal scale (weight) — and many experienced resin crafters prefer weight, because it's more precise than reading a meniscus in a cup.

Step-by-Step Worked Derivation

Take the 24" × 12" panel example at 1/8" thick, 1:1 ratio, 10% waste, and do it by hand.

Step 1 — Raw volume. 24 × 12 × 0.125 = 36 in³.

Step 2 — Add waste. 36 × 1.10 = 39.6 in³.

Step 3 — Convert to fluid ounces. 39.6 × 0.554113 = 21.94 fl oz.

Step 4 — Split by ratio. At 1:1, total parts = 2, so each part = 21.94 ÷ 2 = 10.97 fl oz.

Step 5 — Convert to weight. 10.97 fl oz × 29.5735 = 324.4 mL. Resin: 324.4 × 1.15 = 373.1 g. Hardener: 324.4 × 0.97 = 314.7 g.

Step 6 — True weight ratio. 373.1 ÷ 314.7 = 1.19 : 1, not the 1:1 the volume split suggested — this is exactly why measuring by weight for a 'by volume' ratio without a datasheet's density figures can quietly under- or over-catalyze a batch.

Why Getting the Ratio Exactly Right Matters

Epoxy cures through a chemical reaction between the resin and the hardener, not by evaporation like paint. That means the ratio isn't a matter of taste — it's a stoichiometric requirement.

Too much hardener relative to resin typically leaves the cured piece brittle, and can cause excess heat during cure (exotherm), which risks cracking, yellowing, or clouding in a thick pour.

Too little hardener typically leaves the surface tacky or soft indefinitely, because there isn't enough of the curing agent to react with all the resin.

Inconsistent mixing — even at the correct overall ratio — causes soft or tacky patches, because unmixed resin and hardener sitting next to each other in the same cup never fully react. Most manufacturers recommend mixing thoroughly for a full 3-5 minutes and scraping the sides and bottom of the container repeatedly.

Measuring inaccuracy compounds at scale. A ratio that's 5% off in a 2 fl oz coaster batch is a small absolute error; the same 5% error in a 20-gallon river-table pour is a much larger absolute amount of unreacted material, which is one reason large pours are especially unforgiving of measuring shortcuts.

Realistic Scenarios

Scenario 1 — A small coaster set. 4" × 4" mold, 1/4" deep, 2:1 ratio, 5% waste: 2.33 fl oz total — 1.55 fl oz resin, 0.78 fl oz hardener.

Scenario 2 — A tabletop seal coat. 24" × 12" panel, 1/8" thick, 1:1 ratio, 10% waste: 21.94 fl oz total, split evenly by volume but 373.1 g vs 314.7 g by weight.

Scenario 3 — A river table. 60" × 20" slab void, 1/2" deep, 1:1 ratio, 10% waste: 365.71 fl oz total — about 2.86 gallons, split into 182.86 fl oz of resin and 182.86 fl oz of hardener. At this scale, most crafters pour in stages rather than all at once, both to manage exotherm heat and because most mixing cups don't hold multiple gallons.

A practical note on staged pours: for anything deeper than about 1/2" in one go, check your specific product's maximum recommended pour depth per layer — many tabletop epoxies are only rated for thin coats (around 1/8"-1/4") per layer specifically to manage the heat generated as it cures, and pouring too deep at once can crack or cloud the piece.

Common Epoxy Mixing Mistakes

Eyeballing the ratio instead of measuring precisely. Even 'close enough' by eye is often not close enough — use graduated mixing cups or a scale.
Mixing by volume when the product specifies weight (or vice versa). Always check whether your datasheet's ratio is by volume or by weight; they are not interchangeable without knowing both densities.
Under-mixing. Stirring for 30 seconds is rarely enough. Scrape the sides and bottom of the cup repeatedly across several minutes.
Ignoring temperature. Cold resin and hardener are more viscous and harder to mix thoroughly, and cold ambient temperatures slow curing and can leave a soft surface even at a correct ratio. Most products specify a workshop temperature range.
Pouring too thick in one layer. Deep single pours can overheat during cure, risking cracking, yellowing, or a cloudy finish — check your product's maximum per-layer depth.
Forgetting the waste allowance and running short mid-pour. Running out partway through a large pour, and mixing a second batch to finish it, can create a visible seam line.

What This Calculator Can and Cannot Do

It can:

Calculate exact resin and hardener volume from your project's dimensions and a waste allowance
Split that volume by any mix ratio you specify
Convert the result to weight using resin and hardener densities you provide
Show how the volume ratio and weight ratio can differ

It cannot:

Know your specific product's correct mix ratio or densities — always check the manufacturer's technical data sheet
Calculate volume for irregularly shaped molds automatically — measure the true volume (e.g. by water displacement) for anything that isn't roughly rectangular
Predict cure time, exotherm behavior, or maximum safe pour depth, all of which are product-specific

The honest summary: this calculator gets the geometry and ratio math exactly right. The ratio numbers and densities you enter are only as accurate as your product's datasheet — always verify those against the manufacturer's instructions rather than assuming this page's defaults match your specific epoxy.

Final Summary

The formula worth remembering: Total volume (fl oz) = Length × Width × Thickness (in³) × 0.554 × (1 + Waste%), split by your mix ratio, then converted to weight with Volume × 29.5735 × Density.

Quick reference: a 24" × 12" panel at 1/8" thick needs roughly 22 fl oz of mixed epoxy at a 1:1 ratio; a 60" × 20" river table at 1/2" thick needs roughly 366 fl oz (about 2.9 gallons).

The one thing to actually do: measure by weight with a scale rather than by volume with cups whenever your product's datasheet gives you the density figures to do so — it's more precise and removes meniscus-reading error entirely.

Related tools worth a look: the woodworking board foot & wood movement calculator and wood shrinkage calculator for the wood side of a resin-and-wood project, and the paint calculator for topcoat and finishing quantities. For the deep-pour heat-buildup science and why volume ratios never match weight ratios, see our epoxy resin guide.

Related concepts

Mix ratio

The required proportion of resin to hardener for a two-part epoxy system to cure fully, specified by the manufacturer as either a volume ratio or a weight ratio — the two are not interchangeable without density figures.

Exotherm

The heat released as epoxy resin and hardener chemically react during cure. Larger or deeper pours generate more total heat, which is why many products limit maximum recommended pour depth per layer.

Density (specific gravity)

Mass per unit volume, typically expressed in g/mL for liquid resin components. Because resin and hardener often have different densities, an equal-volume mix does not produce an equal-weight mix.

Frequently Asked Questions

How much epoxy resin do I need for a tabletop?+

Multiply length × width × thickness in inches to get cubic inches, multiply by 0.554 to get fluid ounces, then add a 5-10% waste allowance. A 24" × 12" panel poured 1/8" deep needs about 22 fluid ounces of mixed resin and hardener combined.

What is a resin mix ratio?+

The proportion of resin (Part A) to hardener (Part B) required for the epoxy to cure correctly, written like 1:1 or 2:1. Unlike paint, epoxy cures through a chemical reaction between the two parts, so the ratio must match the manufacturer's specification exactly.

Should I measure epoxy resin by volume or by weight?+

Either works if you use the correct ratio for that measuring method, but weight (using a scale) is generally more precise than volume (using cups), since it removes the error of misreading a liquid's meniscus in a measuring cup.

Why don't equal volumes of resin and hardener weigh the same?+

Because resin and hardener usually have different densities. A 1:1 ratio by volume can produce a weight split like 1.19:1 if the resin is denser than the hardener, which is common for many tabletop epoxy systems.

What happens if I use too much or too little hardener?+

Too much hardener relative to resin can leave the cured piece brittle and generate excess heat during cure. Too little hardener typically leaves the surface tacky or soft indefinitely, since there isn't enough curing agent to fully react with the resin.

How deep can I pour epoxy resin in one layer?+

It depends entirely on the specific product — many tabletop epoxies are rated for thin coats around 1/8" to 1/4" per layer to manage heat buildup during cure, while specialized deep-pour formulations are designed for much thicker single pours. Always check your product's datasheet.

How much waste allowance should I add to an epoxy calculation?+

5% to 10% is typical, covering resin left behind on the mixing cup wall, the stir stick, and small drips. Larger or more complex pours sometimes warrant a higher allowance.

Is this epoxy resin calculator free?+

Yes — completely free, no registration, and no data leaves your browser. Every figure recalculates instantly as you change an input.

Formula

Epoxy resin mixing formula

Fill volume (in³) = Length × Width × Thickness × (1 + Waste%). Total (fl oz) = Volume (in³) × 0.554. Resin = Total × RatioA ÷ (RatioA + RatioB); Hardener = Total × RatioB ÷ (RatioA + RatioB). Weight (g) = Volume (fl oz) × 29.5735 × Density (g/mL).

Mixing by volume and mixing by weight give different splits whenever resin and hardener have different densities — this calculator shows both so you can measure with a scale or with graduated cups.

Step by step

How the calculation works

1Enter the length, width and pour thickness of your project in inches.
2Add a waste allowance for mixing cup residue and stir-stick loss.
3Enter your product's mix ratio (check the datasheet — common ratios are 1:1 and 2:1 by volume).
4Enter resin and hardener densities if you want an accurate weight split, or use the defaults for a typical tabletop epoxy system.

Example

Worked example — 24" × 12" panel, 1/8" thick, 1:1 ratio

Related guides

Learn more about this calculation

Guide