Introduction
This resin calculator tells you how much epoxy resin you need for your project. Enter your shape and size, and it gives you the answer in fluid ounces, milliliters, liters, gallons, and cubic inches.
It works for rectangles, circles, triangles, and ovals. You can pick a thin coating (like a flood coat on a table top) or a deep casting pour (like a mold or river table). Add the number of coats and a small waste buffer for what sticks to the mixing cup.
The calculator also splits your total into Part A (resin) and Part B (hardener). You get the split by volume using ratios like 1:1, 2:1, 3:1, or your own custom ratio. You also get the split by weight in grams and ounces, which is handy if you mix on a scale.
On top of that, it suggests a kit size to buy and can estimate your cost if you enter a price per fluid ounce. A step-by-step solution shows the math, so you can check the numbers yourself. Always double-check the mix ratio printed on your own resin label, since it changes from brand to brand.
How to use our Resin Calculator
Enter your project shape, size, pour depth, and mix ratio, and the resin calculator tells you how much epoxy resin you need in cubic inches, fluid ounces, milliliters, liters, and gallons, plus the Part A and Part B split, a kit size to buy, and the cost.
Project Shape: Pick the shape of your piece: rectangle/square, circle/round, triangle, or oval. This sets which size boxes show up.
Application Type: Choose Coating for a thin top layer, or Casting to fill a mold to a set depth.
Mix Ratio: Pick 1:1, 2:1, or 3:1. Choose Custom to type your own Part A and Part B numbers, like 100 and 44. Check your bottle label first.
Resin Formulation: Pick your resin type from the list. This sets the weight split used in the "Mix by Weight" results.
Unit System: Choose Imperial (inches) or Metric (centimeters). You can still change the unit on any single box.
Length and Width: For a rectangle or square, type the two side measurements of your surface.
Diameter: For a round project, type the full width across the middle. The tool cuts it in half to get the radius.
Base and Triangle Height: For a triangle, type the bottom edge and the straight-up height of the face.
Oval Width and Oval Height: For an oval, type the long way across and the short way across.
Depth / Thickness: For casting, type how deep the mold gets filled.
Coating Thickness: For coating, type how thick one layer will be. A normal flood coat is 0.125 in (3.175 mm).
Number of Coats / Pours: Type how many layers you plan to pour. The total volume is multiplied by this number.
Waste Buffer (%): Add extra resin for drips, spills, and what sticks in the cup. 5% is a safe start.
Price per fl oz (USD): Type what you pay per fluid ounce to see a cost estimate. Leave it blank or 0 to hide the cost.
Custom Density (g/cm³): Most epoxy is about 1.1 g/cm³. Change it only if your product lists a different number. This changes the gram and ounce weights.
Calculate and Reset: Click Calculate Resin Amount to see your results, charts, and step-by-step math. Click Reset to start over with the sample numbers.
What Is a Resin Calculator?
Epoxy resin comes in two parts: Part A (resin) and Part B (hardener). You mix them, pour them, and they cure into a hard, glossy solid. The hard part is guessing how much to mix. Too little and your pour comes up short. Too much and you waste costly resin. A resin calculator takes the size of your piece and returns how many fluid ounces, milliliters, or gallons of mixed resin you need.
How Resin Amounts Are Figured Out
The math is simple at its core: area × depth = volume. First you find the surface area of your project, which changes with the shape:
- Rectangle or square: length × width
- Circle: π × radius² (radius is half the diameter)
- Triangle: ½ × base × height
- Oval: π × (width ÷ 2) × (height ÷ 2)
Then you multiply that area by how thick the resin layer will be, and again by the number of coats. That gives cubic inches, which converts to fluid ounces (1 in³ ≈ 0.554 fl oz) and milliliters (1 fl oz ≈ 29.57 mL).
Coating vs. Casting
Coating means a thin, flat layer poured over a top surface, like a table, a bar top, or a wood cutting board. A normal flood coat is about 1/8 inch (3.175 mm) thick. Casting means filling a mold or a deep cavity, like a river table, a paperweight, or a resin block. Casting uses much more resin because the depth is much greater.
This matters for more than money. Casting resin is made to cure slowly in deep pours so it does not overheat. Coating resin cures fast and can crack, yellow, or smoke if you pour it too deep. Always check the max pour depth on your bottle.
Mix Ratios: Volume and Weight
Every resin brand has its own mix ratio. Common ones are 1:1, 2:1, and 3:1 by volume. Some brands list the ratio by weight instead, such as 100:44. These are not the same thing, because resin and hardener have different densities. Mixing by weight needs a digital scale; mixing by volume needs marked cups. Either way, follow the exact ratio printed on your label. Guessing or "eyeballing" leads to soft, sticky, or cloudy resin that never fully hardens.
Why You Should Add a Waste Buffer
Some resin always gets left behind. It clings to the sides of your mixing cup, sticks to the stir stick, drips over the edge of the piece, or gets scraped off. Adding a 5% to 10% buffer covers that loss. For big or tricky pours, go closer to 10%. Running out mid-pour is much worse than having a little extra, since epoxy starts to set as soon as it is mixed and you cannot pause to mix a fresh batch.
Quick Tips for Better Pours
- Work at room temperature, around 70 to 75°F (21 to 24°C). Cold resin traps bubbles and cures slowly.
- Mix for a full 3 minutes, scraping the sides and bottom of the cup.
- Pour into a second clean cup and stir again for the best cure.
- Level your table first. Resin flows to the low side.
- Tape the underside edges of coating projects to catch drips.
- Pop bubbles with a heat gun or torch, moving fast and staying a few inches away.
- Wear gloves and work in a room with fresh air.
Buying the Right Kit Size
Resin kits usually sell in 8 oz, 16 oz, 32 oz, 64 oz, and 1-gallon sizes. That total is the combined volume of Part A and Part B together, so a 32 oz kit gives you 32 oz of mixed resin. Pick the smallest kit that still covers your total plus buffer. Buying a bigger kit often costs less per ounce, but opened resin has a shelf life of about 6 to 12 months, so only size up if you have more projects planned.