Resin Calculator
Calculate exactly how much resin you need for epoxy, polyester, or polyurethane projects with mix ratio breakdowns.
Project Setup
Mix Ratio Breakdown
What is a Resin Calculator?
A resin calculator is an essential tool for anyone working with epoxy, polyester, or polyurethane resins for casting, coating, or art projects. Getting the right amount of resin is critical — too little means an incomplete pour that can't be easily fixed, while too much means wasted money on expensive material. This calculator takes your project dimensions (rectangular, circular, or irregular volume), applies a waste factor, and calculates the exact amount of resin needed in fluid ounces and gallons. It also breaks down the mix ratio into separate resin and hardener quantities based on your chosen resin type, calculates pigment and additive amounts, and provides a cost estimate. Whether you're making river tables, jewelry, countertop coatings, or art pieces, this tool ensures you mix the right amount every time. All calculations run in your browser with no data collection.
How to Use the Resin Calculator
- Select your shape: Choose rectangular, circular, or irregular (if you already know the volume).
- Choose resin type: Select epoxy, polyester, or polyurethane — each has different mix ratios and costs.
- Set project type: Choose coating (thin pour) or casting (deep pour) to adjust the depth input.
- Enter dimensions: Input length, width, and thickness/depth in inches, or enter volume directly for irregular shapes.
- Adjust waste factor: Set the waste percentage (10% is standard for most projects).
- Set pigment percentage: Enter the percentage of pigment or additives you plan to use (typically 3-8%).
- Review results: See total resin needed, mix ratio breakdown (Part A and Part B), pigment amount, and estimated cost.
Features
- Three shape options: Rectangular, circular, and irregular volume input for any project shape.
- Three resin types: Epoxy (2:1), polyester (100:2 MEKP), and polyurethane (1:1) with accurate mix ratios.
- Coating vs casting modes: Optimized input steps for thin coatings (1/16") or deep casting pours.
- Mix ratio calculator: Automatically breaks down total volume into exact resin (Part A) and hardener (Part B) quantities.
- Pigment calculator: Calculate the exact amount of colorant or additive based on your desired percentage.
- Waste factor adjustment: 5-25% waste factor to account for mixing cups, stirring sticks, and overflow.
- Cost estimator: Estimates material cost based on current average resin prices per gallon.
- Coverage area display: Shows the surface area for coating projects in square feet.
Use Cases
- River tables: Calculate epoxy needed to fill the river channel in a live-edge wood table.
- Countertop coatings: Determine the right amount of epoxy for a bar top or countertop coating.
- Resin art: Calculate resin for petri dishes, geode art, ocean art, and other resin art pieces.
- Jewelry making: Measure exact amounts for small silicone mold pours for pendants and earrings.
- Fiberglass work: Calculate polyester resin quantities for boat repair and fiberglass lamination.
- Industrial coatings: Estimate polyurethane resin for floor coatings and protective finishes.
Tips & Tricks
- For deep pours (over 1 inch), use a deep-pour epoxy formula — standard table-top epoxy can overheat and crack in thick layers.
- Always measure resin and hardener by volume, not weight, unless your manufacturer specifically provides weight-based ratios.
- Mix thoroughly for at least 3-5 minutes, scraping the sides and bottom of your mixing container to avoid sticky spots.
- Use a 10% waste factor for simple pours and 15-20% for complex molds with many details or undercuts.
- Add pigments after mixing resin and hardener together — adding pigment to just one part can throw off the mix ratio.
Resin Calculator vs Alternatives
Most resin calculators online only handle one resin type (usually epoxy) and don't account for mix ratios, waste, or pigment. Others are built into resin manufacturer websites and only work with their specific product densities. ToolMagic's resin calculator supports three resin types with accurate mix ratios, handles three shape inputs including irregular volumes, includes pigment percentage calculation, and provides cost estimates — all free, instant, and private in your browser.
Frequently Asked Questions
How much epoxy resin do I need for a table top?
For a standard table-top coating (1/8 inch thick), you need about 12 oz of mixed epoxy per square foot. A 6-foot by 3-foot table would need about 1.7 gallons. Use our calculator with your exact dimensions for a precise estimate including waste factor.
What is the mix ratio for epoxy resin?
Most epoxy resins use either a 1:1 or 2:1 ratio (resin to hardener) by volume. Our calculator uses a 2:1 ratio which is most common for table-top and casting epoxies. Always check your specific product's instructions.
How do I calculate resin for a round mold?
Select the "Circular" shape option, enter the diameter and depth, and the calculator automatically uses the formula (π × r² × depth) to calculate the volume. It then converts to ounces and gallons of resin needed.
What is the difference between epoxy, polyester, and polyurethane resin?
Epoxy is the most popular for art and woodworking — it's clear, strong, and UV-resistant. Polyester is cheaper and used mainly for fiberglass work. Polyurethane is flexible and impact-resistant, ideal for industrial coatings and casting rigid parts.
How much pigment should I add to resin?
Most resin pigments are added at 3-8% of the total mixed volume. Too much pigment can interfere with curing. Opaque colors need 5-8%, while translucent effects need only 1-3%. Our calculator lets you set any percentage from 0-15%.
What waste factor should I use for resin?
Use 10% for simple open pours and coatings. Use 15-20% for complex molds or projects where resin may stick to mixing cups and tools. For very small projects (under 8 oz), use 15-20% since proportional waste is higher.
How much does epoxy resin cost?
Epoxy resin typically costs $50-$80 per gallon for quality table-top or casting formulas. Budget brands may be $30-$40 per gallon. Polyester is cheapest at around $25-$40 per gallon. Polyurethane is typically $60-$100 per gallon.
Can I pour resin thicker than 1 inch at a time?
Standard table-top epoxy should only be poured 1/8 to 1/4 inch at a time. Deep-pour or casting epoxy can handle 1-2 inches per pour. Pouring too thick causes overheating (exothermic reaction) which can crack, yellow, or warp your project.
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