Epoxy Calculator - Resin Volume, Weight & Mix Ratio Estimator
Use this free epoxy calculator to compute total resin volume in fluid ounces, gallons, or liters, estimate required weight, and divide Part A and Part B mix ratio amounts.
Epoxy Calculator
Results
What Is Epoxy Calculator?
Our free online epoxy calculator serves as a digital layout assistant for makers, woodworkers, and DIY enthusiasts aiming to estimate the exact quantity of resin required for casting projects. This epoxy calculator estimates volume and weight parameters with high precision. Epoxy resin is a two-part polymer compound comprising a resin (Part A) and a hardener (Part B) that, when combined in exact ratios, cures into a solid, high-gloss plastic shell. Because epoxy is expensive and has a limited working window (pot life) once combined, mixing too much leads to costly waste, while mixing too little can ruin a multi-layer pour by forcing builders to quickly mix a second batch. Utilizing this online calculator, creators can determine the exact physical volumes, liquid units, and weight requirements for river tables, deep-pour molds, countertop laminates, and garage floor coatings.
Whether you are coating a concrete floor with a protective glossy shield, casting delicate jewelry in small silicone molds, or building a premium solid oak river table centerpiece, calculating the correct quantities of liquid polymer is crucial. Standard coating resins differ significantly from deep-pour casting resins in both curing speed and heat dissipation profiles. This epoxy calculator helps DIY hobbyists and professional builders select the right mixing proportions to avoid failures like exothermal yellowing, cracking, or soft sticky cures. By planning your pour beforehand, you ensure that Part A and Part B react at a controlled rate, ensuring a crystal-clear, durable surface finish.
For best results, always measure your mold dimensions at multiple points. Wood slices and live-edge slabs are rarely uniform in thickness or width; taking the average width and maximum depth ensures you do not run short of mixed resin midway. Additionally, seal any porous surfaces (like dry timber or concrete) with a thin brush-on coat of resin before performing the main pour. This sealing coat locks the air inside the wood fibers, preventing pesky bubbles from rising and becoming trapped in your crystal-clear finish during the main casting phase.
To coordinate raw wood material dimensions before pouring resin, our Lumber Calculator estimates board foot volumes.
How Epoxy Calculator Works
The math of this epoxy calculator is straightforward: we solve for three-dimensional capacity (cubic inches or cubic centimeters) and translate it to fluid measurements. For rectangular molds, we calculate Length × Width × Depth. For circular shapes, we multiply pi × Radius² × Depth. Since some material is lost in mixing cups or absorbed by porous wood grain, we apply a waste factor (typically 5% to 15%) to find the target mixing volume.
To calculate the liquid capacity from physical dimensions, this epoxy calculator uses the standard conversion factor of 1.80469 cubic inches per US fluid ounce (or 1 cubic inch ≈ 0.554 fl oz). For metric projects, the calculator computes the volume in cubic meters and multiplies by 1,000 to determine liters, converting to weight by applying the specific gravity density of the mixed resin. Estimating weight is essential to verify if your supporting table frame or structure can handle the load of the cured pour.
Circular Volume (in³) = π × [Diameter (in) / 2]² × Depth (in)
Total Volume with Waste (in³) = Volume × [1 + Waste Factor (%) / 100]
Fluid Ounces (fl oz) = Total Volume (in³) ÷ 1.80469
Worked Example
Scenario: Pouring a rectangular mold of 48 in × 24 in to a depth of 1.5 in with a 1:1 ratio and a 10% waste factor.
- Compute physical volume: 48 × 24 × 1.5 = 1,728 cubic inches (in³).
- Include 10% waste factor: 1,728 × 1.10 = 1,900.8 in³.
- Convert to fluid ounces: 1,900.8 / 1.80469 = 1,053.26 fl oz.
- Divide Part A and Part B (1:1): Part A = 526.63 fl oz, Part B = 526.63 fl oz.
- Convert to weight (density 1.1 g/cm³): 1,900.8 in³ × 0.0163871 = 31.15 Liters. 31.15 L × 1.1 = 34.27 kg, which converts to 75.54 lbs.
Just as resin layouts require precise depth coordinates, stringer plans follow stair geometries solved in our Stair Calculator.
Key Concepts & Chemistry Parameters
Part A and Part B
Epoxy systems consist of a base resin (Part A) and a chemical activator or hardener (Part B) that must be combined in precise volumetric proportions to cure successfully.
Volumetric Mix Ratio
The volumetric proportion required for the chemical reaction, most commonly 1:1 or 2:1 for deep pours, though some casting systems require 3:1 or 4:1 ratios.
Waste Factor Margin
An additional percentage (typically 5% to 15%) added to the project volume to account for spills, material left on container walls, and absorption into porous wood surfaces.
Deep Pour Limitations
Specialized casting resins cure slowly to release heat. Pouring standard coating epoxy deeper than 1/4 inch or deep-pour resin deeper than 3 inches in a single stage can cause exothermal cracking.
To calculate the structural wood frames surrounding your tabletop mold, consult our Framing Calculator.
How to Use This Calculator
- 1 Step 1: Select your project geometry, choosing between a rectangular area (standard river tables and molds) or a circular tabletop.
- 2 Step 2: Enter your dimensional inputs: length, width (or diameter), and the target pour depth in inches.
- 3 Step 3: Choose the manufacturer-specified mix ratio (e.g. 1:1, 2:1, or 3:1 volumetric ratio).
- 4 Step 4: Set your waste factor margin to account for wood absorption and mixing losses (10% is recommended).
- 5 Step 5: Review the calculated liquid outputs (ounces, gallons, liters) and weight requirements for Part A and Part B.
Benefits of Using This Calculator
Our epoxy calculator provides essential advantages for woodworkers, makers, contractors, and DIYers looking to execute flawless resin applications:
- • Saves Project Budget: Prevents expensive over-purchasing of premium resin kits. By entering precise measurements, you only buy and mix the exact quantities required for your project.
- • Ensures Curing Success: Ensures chemical success by dividing Part A (resin) and Part B (hardener) by exact volumetric ratios (e.g. 1:1, 2:1) specified by the manufacturer.
- • Safety Margin Planning: Minimizes project disruption by calculating a reliable safety waste margin (5% to 20%) to compensate for container transfer residue and wood grain absorption.
- • Multi-Unit Output: Enables flexible preparation by providing outputs in both US fluid ounces, gallons, milliliters, and metric liters so you can measure with any container or scale setup.
- • Safety & Exotherm Alerting: Prevents dangerous exothermal heat spikes, cracking, and yellowing by warning against pouring standard coating or casting epoxies past safe single-pour depth thresholds.
Factors That Affect Your Results
Wood Surface Porosity
Unsealed live-edge wood slabs absorb liquid resin into their pores, which requires a higher waste factor (10% to 15%) to avoid running short.
Resin Density and Specific Gravity
Liquid epoxy is heavier than water. Standard mixtures have a density of 1.1 g/cm³, meaning a liter of mixed epoxy weighs 1.1 kilograms (or 2.42 lbs).
Ambient Temperature
Temperature affects viscosity and curing speed; cold rooms make resin thick and difficult to mix, whereas warm rooms accelerate pot-life limits.
For deep molds that exceed the recommended maximum single-stage thickness (typically 2 to 3 inches for casting resin), it is necessary to pour in multiple sequential layers. Allow the first layer to cool and partially cure to a firm gel state before pouring the next stage. This layering technique prevents the total exothermal heat energy from concentrating to unsafe levels, ensuring your project does not scorch, yellow, or warp during the cure cycle.
- • This calculator assumes standard flat surfaces; irregular voids or multi-species river tables require averaging thickness inputs.
For wall finishes or ceiling panels after casting resin projects, check our Drywall Calculator.
- TotalBoat Technical Resources: TotalBoat Resin Calculations
- Woodworking Casting Guides: Blacktail Studio Resin Tables
Frequently Asked Questions
Q: How do you calculate how much epoxy is needed?
A: To calculate epoxy requirements, multiply Length (in) × Width (in) × Depth (in) to find the volume in cubic inches, then divide by 1.80469 to find the total liquid volume in fluid ounces. If you are calculating metric dimensions (cm), multiply Length (cm) × Width (cm) × Depth (cm) to get cubic centimeters, which is equivalent to milliliters. Divide the milliliters by 1,000 to convert to liters. Knowing the exact cubic volume lets you purchase the correct amount of material and prevents the mixing of excess product that would only go to waste.
Q: What is a standard waste factor for epoxy projects?
A: A waste factor of 5% to 10% is recommended for smooth non-porous molds (like silicone or polished melamine), while 10% to 15% is ideal for live-edge wood river tables to compensate for absorption, uneven wood edges, and material left behind on mixing container walls. For large industrial floor coatings or rough concrete slabs, a waste factor of 15% to 20% is safer because concrete texture can drink up significantly more resin than anticipated.
Q: How do you calculate epoxy volume for a round table?
A: For circular tables or cylinder molds, calculate volume by multiplying the radius squared times pi times the pour depth: Volume = pi * Radius² * Depth. To find the radius, divide the diameter of the table by 2. For example, a 36-inch round table has an 18-inch radius. Multiply 18 × 18 × 3.14159 × Depth to find the total volume in cubic inches, then convert it to fluid ounces or liters as needed for mixing.
Q: What density is assumed for epoxy weight calculations?
A: This calculator assumes a standard mixed epoxy density of 1.1 g/cm³ (or 1.1 kg/L). This value can be adjusted between 0.8 and 1.5 based on your manufacturer's specific gravity spec. Weight calculations are critical because large pours can add substantial load to furniture legs or flooring. For example, a river table with 10 gallons of epoxy adds about 92 pounds of weight, excluding the wood slabs.
Q: How does the mix ratio affect Part A and Part B amounts?
A: The mix ratio divides the total calculated liquid volume. A 1:1 ratio splits the volume equally (50% Part A and 50% Part B by volume), while a 2:1 ratio requires two-thirds (66.7%) Part A resin and one-third (33.3%) Part B hardener. Always check if the manufacturer specifies the ratio by volume or by weight, as they differ since Part A and Part B have slightly different specific gravities.