Resin Calculator

Resin Calculator: Exact Part A & Part B Epoxy Volumes in mL and Fluid Ounces

Epoxy resin chemistry is completely unforgiving of guesswork. Eyeballing a 2:1 deep-pour casting kit off by just 6% leaves a $400 black-walnut river slab permanently tacky in the center, while mixing 150 mL too little during a timed tabletop flood coat forces a frantic second batch that cures with a visible ridge line under raking light. Whether you are preserving wedding bouquets inside a 6-inch sphere mold, casting cylinder coasters, or pouring a 1/8-inch bar-top glaze, this Resin Calculator computes exact geometric volume, adds cup-cling overage, and splits your batch into ready-to-pour Part A and Part B amounts in both milliliters and US fluid ounces.

What Is a Resin Calculator?

A resin calculator is a volumetric stoichiometry and casting takeoff tool built for woodworkers, resin artists, boatbuilders, and composite makers. Instead of leaving you to convert cubic inches into milliliters and divide awkward fractions like 2/3 and 1/3 in your head while wearing nitrile gloves, it handles five mold geometries plus flat surface coatings and divides total liquid volume across any standard or custom hardener ratio.

Consider Nina, a botanical preservation artist casting dried bridal roses inside a 15 cm diameter sphere silicone mold using a slow-cure 2:1 deep-pour floral casting epoxy. Guessing “around a liter” would leave the top third of her sphere empty! Running a 15 cm sphere (`r = 7.5 cm`) through the Mold Volume tab reveals an empty cavity volume of `1,767 mL` (`59.8 fl oz`). Accounting for roughly 15% flower displacement and adding a 10% cup-residue buffer across three layered pours, Nina knows to have a 2-liter kit on the bench—splitting each batch cleanly into two parts Part A resin and one part Part B hardener. For oversized industrial drums or aquarium vats, check our Tank Volume Calculator.

How the Resin Calculator Formula Works (Step-by-Step Example)

Because 1 cubic centimeter (cm³) = 1 milliliter (mL), metric mold math translates directly into graduated mixing-cup markings, while inch measurements convert via 1 in³ = 16.3871 mL and 1 US fl oz = 29.5735 mL = 1.80469 in³:

• Box / River Channel: V = Length × Width × Depth
• Cylinder (Coasters / Pillar Molds): V = π × (Diameter ÷ 2)² × Height
• Hemisphere (Paperweight Dome): V = (2 ÷ 3) × π × (Diameter ÷ 2)³
• Full Sphere: V = (4 ÷ 3) × π × (Diameter ÷ 2)³

Once raw volume is multiplied by (1 + Waste% ÷ 100) × Mold Qty, Part A and Part B split proportionally for an A : B volume ratio:

Part A = Total Volume × [ A ÷ (A + B) ]  |  Part B = Total Volume × [ B ÷ (A + B) ]

Let’s trace a Box Mold (`10 cm × 10 cm × 5 cm`) using a 2:1 Deep-Pour Epoxy with 10% Waste:

• Raw Mold Cavity: 10 × 10 × 5 = 500 cm³ = 500 mL.
• With 10% Waste Allowance: 500 × 1.10 = 550 mL (550 ÷ 29.5735 = 18.6 fl oz total).
• Part A (Resin, 2/3 share): 550 × (2 ÷ 3) = 367 mL (12.4 fl oz).
• Part B (Hardener, 1/3 share): 550 × (1 ÷ 3) = 183 mL (6.2 fl oz).

Epoxy Coverage, Max Pour Depth & Mix Ratio Reference Table

Not all epoxies are interchangeable: fast 1:1 coating resins overheat if poured thick, whereas thin 2:1 or 3:1 deep-pour casting systems take 72 hours to gel and run straight off flat canvases. Match your resin chemistry and volume budget using the shop benchmarks below (measuring large bar-top dimensions in feet first? Convert your surface in our Square Footage Calculator or Unit Converter).

Volume vs. Weight Ratios, Double-Cup Mixing & Exotherm Control

Two technical mistakes ruin more epoxy pours than everything else combined: weighing a volume-rated kit on a gram scale and scraping unmixed sidewall residue onto the project. Because bisphenol-A epoxy resin (`~1.15 g/mL`) weighs roughly 18% more per milliliter than cycloaliphatic amine hardener (`~0.97 g/mL`), pouring “100 g + 100 g” of a 1:1-by-volume tabletop resin throws the stoichiometry off by nearly a fifth—leaving soft spots that indent with a fingernail months later. Only use a gram scale if the manufacturer’s Technical Data Sheet (TDS) prints an explicit mix ratio by weight (such as `100 : 83` or `100 : 44 by weight`), which you can scale precisely using our Percentage Calculator.

To guarantee zero uncured streaks, professional makers use the two-cup transfer method: measure Part A and Part B into calibrated Cup #1, stir slowly for 3 full minutes scraping sides and stick, then pour the blended liquid into a clean Cup #2 and stir for 60 more seconds before pouring into your mold. Never scrape the last cling film out of Cup #1 onto a finished tabletop—that boundary film is where unmixed Part A hides, and your 10% waste allowance in the calculator already paid for leaving it behind in the cup!

Common Mistakes People Make With a Resin Calculator

• Forgetting wood, stone, or floral displacement in river tables: Measuring outer form dimensions (`72″ × 30″ × 2″`) calculates resin for an empty rectangular tub (`18.7 gallons`)! Measure only the average width of the open river gap between live-edge slabs—or subtract wood board volume first.
• Confusing diameter with radius on cylinder and sphere molds: Entering `10 cm` when a formula expects radius vs. diameter changes sphere volume by a factor of `8×` (`2³`). Our calculator explicitly asks for full Diameter across the mold opening so you can measure straight across with a ruler.
• Over-torching silicone molds to pop surface bubbles: Waving a butane torch across silicone edges fuses silicone permanently to curing epoxy, tearing your mold during demolding. Use a quick mist of 91%–99% isopropyl alcohol or a warm heat gun on silicone molds, saving propane torches solely for wood flood coats.

Select your mold shape or surface dimensions above, verify your bottle’s exact volume ratio before uncapping Part B, and copy your mL and fluid-ounce targets straight to your workbench note card.

Related Calculators: Tank Volume Calculator · Unit Converter · Square Footage Calculator · Linear Feet Calculator