Epoxy Resin Volume & Part A:B Mixing Ratio Calculator (Oz, ml, Grams)
Running short of resin mid-pour ruins a project, and mixing an inaccurate Part A:B ratio can leave a cast that never fully cures. This calculator converts your mold dimensions into exact fluid ounces, millilitres and grams, then splits the total by your resin's mix ratio.
Mix 3.66 oz of Part A with 3.66 oz of Part B for a 1:1 ratio pour, including a 10% waste buffer.
| Measure | Value |
|---|---|
| Mold volume | 12.00 cu in |
| Base resin (no buffer) | 6.65 fl oz |
| Waste buffer applied | 10% |
| Total fl oz | 7.31 |
| Total ml | 216 |
| Total grams | 238 |
| Part A | 3.66 oz / 119 g |
| Part B | 3.66 oz / 119 g |
Formula & step-by-step maths
- Depth
- Pour thickness in inches
- Waste%
- Buffer for spillage/residue
- RatioA:RatioB
- Resin to hardener mix ratio
Why the waste buffer matters
Resin left in mixing cups, on stir sticks, and on the sides of measuring containers typically wastes 5-15% of what you pour. A 10% buffer is a safe default for small pieces; increase it to 15-20% for intricate molds with lots of surface area relative to volume.
Rectangle, cylinder and round slab formulas
Rectangular and slab molds use length × width × depth in cubic inches. Round shapes — cylinders, coasters, discs — use the circle area formula π × radius² × depth, where radius is half the diameter you enter in the length field.
Converting cubic inches to fluid ounces and grams
One cubic inch holds approximately 0.554 fluid ounces of liquid. Because most casting resins sit close to 1.1 grams per millilitre once mixed, converting ounces to millilitres (×29.5735) and then to grams (×1.1) gives a close-enough weight for a kitchen or jewellery scale.
Reading your specific mix ratio
Manufacturers label ratios by volume or by weight — always check which one your product uses. If your resin specifies a weight-based ratio, weigh both parts on a scale rather than relying purely on the ounce figures here.
Common resin quantities by project
| Project | Typical volume | Approx. total resin |
|---|---|---|
| Jewellery pendant mold | 1-2 cu in | 0.5-1 fl oz |
| Coaster (4in round, 0.25in) | 3.1 cu in | 1.7 fl oz |
| 8x10in tray, 0.25in deep | 20 cu in | 11 fl oz |
| River table (36x12in, 1in gap avg) | ~90 cu in | 50 fl oz |
| Bar top (72x24in, 0.125in) | 216 cu in | 120 fl oz |
| Tumbler coating (16oz cup) | N/A | 1-2 fl oz |
People also ask
How much resin do I need for a mold I don't know the exact shape of?
Fill the mold with water first, then measure the water volume in fluid ounces — that is your true target volume, more accurate than any geometric formula for irregular shapes.
What happens if I get the mix ratio wrong?
Too much hardener causes rapid, hot curing with bubbling and cracking; too little leaves a sticky, permanently soft surface. Always measure by the manufacturer's exact ratio, not by eye.
Should I measure resin by volume or weight?
Weight is more accurate because viscosity differences make volume measurements imprecise, especially with thick tabletop resins — use a gram scale whenever the product's instructions specify weight ratios.
Why is my resin calculator result different from the bottle's coverage chart?
Coverage charts assume a specific thickness, usually 1/8 inch per coat; this calculator uses your exact depth input, which is more accurate for anything other than that standard thickness.
Can I pour resin thicker than the depth I calculated?
Most casting resins have a maximum safe pour depth (often 0.5-2 inches) before excess heat causes cracking or yellowing — check your product's exothermic limit before scaling up depth.
How much extra should I mix for a river table?
Because deep pours often need multiple layers, add a 15-20% buffer per layer and always mix slightly more than calculated rather than running short mid-pour.
Does temperature affect how much resin I need?
No, temperature affects cure time and viscosity, not volume, though warmer resin flows more easily and self-levels better into corners.
Is 1.1 g/ml density accurate for all resins?
It's a close average; most epoxy casting and tabletop resins fall between 1.05 and 1.15 g/ml combined, so this is accurate within a few percent for weight estimates.
Can I use this calculator for silicone mold making instead of resin?
The volume math is identical, but silicone mix ratios and densities differ, so check your specific silicone product's ratio and density before using the weight outputs.
Why does my resin look cloudy or have bubbles after following this exactly?
Volume accuracy doesn't fix mixing technique — under-mixing causes cloudiness and bubbles, so always mix for the full time recommended (typically 3-5 minutes) and consider a heat gun pass to release trapped air.
Three worked examples
Same engine, three different starting points — useful if you want to see how sensitive the answer is before you type your own numbers in.
Example 1: length (inches, or diameter for round/cylinder) 6.24 in, mold shape "Rectangle / slab"
On the lower / more conservative end. Mix 2.85 oz of Part A with 2.85 oz of Part B for a 1:1 ratio pour, including a 10% waste buffer.
Example 2: length (inches, or diameter for round/cylinder) 8 in, mold shape "Rectangle / slab"
A typical middle-of-the-road setup. Mix 3.66 oz of Part A with 3.66 oz of Part B for a 1:1 ratio pour, including a 10% waste buffer.
Example 3: length (inches, or diameter for round/cylinder) 10.4 in, mold shape "Cylinder"
On the higher / more demanding end. Mix 6.47 oz of Part A with 6.47 oz of Part B for a 1:1 ratio pour, including a 10% waste buffer.
Quick answers about the Epoxy Resin Volume & Mix Ratio
What exactly does the Epoxy Resin Volume & Mix Ratio work out?
Running short of resin mid-pour ruins a project, and mixing an inaccurate Part A:B ratio can leave a cast that never fully cures. You enter mold shape, length (inches, or diameter for round/cylinder), width (inches, ignored for cylinder/round) and depth / thickness (plus 2 more optional details) and the result panel updates straight away, so you can compare two or three versions of the same question in a few seconds.
What do I need before I start?
Only 6 fields: mold shape, length (inches, or diameter for round/cylinder), width (inches, ignored for cylinder/round), depth / thickness, mix ratio (A:B) and waste buffer. Nothing else is needed and nothing is stored.
How is it calculated — why the waste buffer matters?
Resin left in mixing cups, on stir sticks, and on the sides of measuring containers typically wastes 5-15% of what you pour. The same maths runs inside this page, so hand-checking the result on paper gives you the identical figure.
Why do two calculators give me different answers for epoxy Resin Volume & Mix Ratio?
Rectangular and slab molds use length × width × depth in cubic inches. Different sites pick different assumptions, so always check which method a calculator states before you trust the gap between two numbers.
What does the "Common resin quantities by project" table on this page tell me?
It is the reference range this tool works against — 6 rows from "Jewellery pendant mold" (1-2 cu in) up to "Tumbler coating (16oz cup)" (N/A). Use it to sanity-check whether the number you just calculated sits where you expected it to.
Which mold shape should I pick?
The dropdown offers 3 choices — Rectangle / slab, Cylinder and Round slab (disc). Pick the one that matches your real situation rather than the one you would like to be true; mold shape usually moves the final figure more than any other single input, so it is worth running it twice with the option above and below your guess.
Do I have to press a button or reload the page to see the result?
No. Epoxy Resin Volume & Mix Ratio runs completely inside your browser, so the moment you change a value the cards recalculate — there is no submit step, no page reload and no waiting for a server round trip. That also means it keeps working on a weak or intermittent mobile connection.
Is it free, and do you keep what I type?
It is free with no sign-up, no app install and no usage limit. Nothing you enter into Epoxy Resin Volume & Mix Ratio leaves your device — the calculation is JavaScript running locally, so there is no upload of your figures to DrHint or anyone else.
Can I use it on a phone?
Yes — the layout stacks to a single column on small screens and the number fields open the numeric keypad on both Android and iOS. Many people bookmark this page or add it to their home screen and re-open it whenever the question comes up.
Anything to be careful about with the result?
Fill the mold with water first, then measure the water volume in fluid ounces — that is your true target volume, more accurate than any geometric formula for irregular shapes. Treat the output as a well-grounded estimate for planning, not as a professional, legal or medical decision on its own.
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