Resin Calculator
Example measurements are shown. Replace them with the empty space the mixed resin will actually occupy.
On intentional navigation, your measurements are sent to this site in the URL and browser history. Do not enter sensitive information.
NextEstimate the mixed epoxy needed for a rectangular cavity, a circular mold, a coating with a known surface area or a project whose required mixed volume is already known. The calculator works from the finished dimensions or known volume, adds the allowance you choose for losses, and divides the total into resin Part A and hardener Part B using the ratio basis printed by your manufacturer. It is a planning aid, not a substitute for the product label, Technical Data Sheet (TDS) or Safety Data Sheet (SDS): maximum pour depth, batch size, working temperature and mix ratio are specific to each resin system.
How to calculate resin for a pour
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1
Describe the project
Choose a rectangular cavity, circular mold, known-area coating or known mixed-volume calculation, select your measurement units, and enter only the active measurements. Measure the actual cavity or coated area rather than the outside of the mold.
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2
Copy the correct mix ratio
Select whether the manufacturer states A:B by volume or by weight, then enter that ratio exactly. A 2:1 volume ratio is not automatically a 2:1 weight ratio because resin and hardener can have different densities.
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3
Plan the mix and the pours
Review the geometric volume, allowance, mixed total and separate Part A and Part B amounts. Before mixing, compare the result with the product-specific maximum depth, maximum batch volume, temperature range and recoat instructions.
Resin volume formulas
The calculation begins with the physical volume that the mixed resin must occupy:
- Rectangle or square:
volume = length × width × depth - Circle:
volume = π × (diameter ÷ 2)² × depth - Known surface area:
volume = area × depth - Known mixed volume: enter the required volume directly, then add only the allowance that has not already been included
Keep every dimension in a compatible unit before multiplying. For example, a 2 m² surface covered to 3 mm needs a geometric volume of 6 L. A cavity measuring 50 cm × 20 cm × 1 cm needs 1,000 cm³, which is 1 L, before any allowance.
An allowance covers resin left on mixing tools, minor measurement uncertainty and small pouring losses. If the geometric requirement is 1 L and the chosen allowance is 10%, the planned mixed total is 1 × 1.10 = 1.1 L. It is not a correction for badly measured voids, absorbent wood, leaking forms, coated edges or large embedded objects. Measure those separately where possible. TotalBoat likewise describes 5–10% as padding and warns that simple top-volume formulas do not include edges or handling losses.
Split Part A and Part B on the stated basis
For a ratio A:B and a mixed total T:
Part A = T × A ÷ (A + B)
Part B = T × B ÷ (A + B)
A 2:1 by-volume system with a 6 L mixed total therefore needs 4 L of Part A and 2 L of Part B. A 100:42 by-weight system with a 1,420 g mixed total needs 1,000 g of Part A and 420 g of Part B.
| Manufacturer example | Ratio by volume | Ratio by weight | Why the distinction matters |
|---|---|---|---|
| TotalBoat TableTop | 1:1 | 1.2:1 | Equal liquid volumes do not have equal mass |
| EcoPoxy FlowCast | 2:1 | 2.3:1 | The printed mass ratio must be used when weighing |
| Entropy CCR Slow | 2:1 | 100:42 | Component densities change the weight split |
Never convert a volume ratio into a weight ratio by assumption, and never add extra hardener to speed curing. Choose one measurement basis supported by the product instructions and use suitable graduated containers or a scale. If your TDS gives only a volume ratio, use volume; a weight result requires the manufacturer’s weight ratio or verified component densities.
Coating, seal coat and deep casting are different jobs
Porous wood can release air into a flood coat. Manufacturers commonly advise sealing it first, but consumption varies with grain, cracks and absorption. Treat a seal coat as a separate quantity based on that product’s stated spread rate or recommended thickness; do not assume one universal coat allowance. TotalBoat describes sealing porous wood before the flood coat to reduce off-gassing bubbles, while MAS presents 1/16 in as a seal-coat reference and 1/8 in as a flood-coat reference for its calculator workflow.
Deep-pour limits vary even more. WiseBond documents up to 2 in per layer for one deep-pour system. EcoPoxy specifies 13–38 mm per layer and a maximum 30 L pour without additional cooling for FlowCast. MAS ties its guidance to both depth and batch size. Those examples are not interchangeable limits. A calculator can estimate volume, but only the label or current TDS for the exact resin can tell you how many layers to use and how much may be mixed at once.
Exotherm and safe handling
Epoxy cures by a heat-producing chemical reaction. A large mass in a mixing pot can become much hotter than the same material spread into a thin layer. Excess heat can shorten working time and cause bubbles, yellowing, distortion, cracking, smoke or fire. TotalBoat warns that mixed epoxy left in a cup can reach 200–300°F (93–149°C). Do not exceed the manufacturer’s maximum batch volume or pour depth, and do not rely on this estimate to decide that a pour is safe. Check working temperature and humidity, prepare the mould first, and mix only what you can place within the stated working time.
Wear eye protection, protective clothing and chemical-resistant gloves, and work with the ventilation required by the SDS. NIOSH warns that uncured epoxy systems can cause skin irritation and sensitisation; its epoxy guidance recommends thick nitrile or butyl-rubber gloves rather than cotton or latex. Avoid skin contact and read the SDS for the specific resin, hardener, pigments and cleaners before starting.
Sources: TotalBoat epoxy calculator, TotalBoat TableTop TDS, TotalBoat ThickSet TDS, MAS epoxy calculator, MAS Deep Pour guidance, EcoPoxy FlowCast specifications, Entropy CCR technical data, WiseBond Deep Pour guide, and NIOSH epoxy-resin hazard guidance. Product instructions reviewed 16 July 2026.
Frequently Asked Questions
Use the basis stated by the manufacturer for the measuring method you will use. Choose volume when measuring in graduated containers and the product gives a volume ratio; choose weight only when the product gives a weight ratio or the required verified density data. Do not assume the two ratios are numerically identical.
Not automatically. A seal coat is a separate application whose consumption depends on the product, surface area, porosity, cracks and absorption. Calculate it from the manufacturer’s coverage rate or specified thickness, then add it to the main pour plan.
A modest allowance such as 5–10% is common for material left on tools and small handling losses, but it is not universal. Complex forms, absorbent surfaces, edges and uncertain voids may need more careful measurement. Use the percentage as a visible planning choice, not a guarantee.
No universal depth is safe for every epoxy. Maximum depth depends on the exact formulation, total mixed mass, shape, ambient temperature and cooling. Follow the current label and TDS for your resin, including maximum batch volume and any instructions for layered pours.
Curing is exothermic: it releases heat. A deep or concentrated mass sheds heat less effectively than a thin coating, so it can accelerate its own cure and become dangerously hot. Never leave an overheating batch indoors or improvise beyond the manufacturer’s emergency guidance.
Yes, if they occupy a meaningful and measurable part of the cavity. The geometric mould volume assumes the whole space is resin. Subtract a known displacement before adding the handling allowance, while keeping enough margin for irregular gaps and measurement uncertainty.
No. Too much resin or hardener can leave the casting soft, sticky or incompletely cured. Control cure conditions only within the product instructions; measure the stated A:B ratio accurately and use the specified temperature, batch size and layer depth.
Read the product SDS first. NIOSH guidance supports eye protection, protective clothing, appropriate ventilation and chemical-resistant gloves such as thick nitrile or butyl rubber for uncured epoxy systems. Avoid skin contact, and account separately for hazards from pigments, solvents, sanding dust and heat.
No. The values are sent to the site server through Livewire to perform and update the calculation. In the multi-step flow, measurements may also appear in the page URL and browser history when you intentionally continue between steps. Do not enter project names or other sensitive information.
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