Introduction
The first time I poured resin, I eyeballed it. I figured I had been around enough epoxy on job sites — how hard could it be? I mixed what felt like enough, poured it into a serving board mold, and ran out about three-quarters of the way through. If I had used the Resin Volume Calculator before mixing, I would have known exactly how much epoxy to prepare.. Then I scrambled, mixed another batch in a panic, and poured on top of what was already tacking up. The result? A hard, milky line right through the middle of what was supposed to be a clean river table board. I gave that piece to my brother-in-law. He still has it. He also still mentions the line.
That was the day I stopped guessing. That was the day I built the first version of what became the Resin Volume Calculator.
If you are making coasters for your Etsy shop, pouring jewelry trays for a craft fair, or tackling your first encapsulation pour, you need to know exactly how much resin and hardener to mix. Not close. Exactly.
The Simple Math Behind Every Resin Pour
Every resin project comes down to one formula: length × width × depth equals your total volume in cubic inches. That number tells you how much mixed resin you need to fill your mold. But here is where people get tripped up — that total volume is your mixed amount. You still have to split it between resin and hardener according to your ratio.
The Resin Volume Calculator does both steps for you. You punch in your mold dimensions, pick your shape, and tell it your mix ratio. It spits back three numbers: resin volume, hardener volume, and total. That is it.
I co-created this calculator specifically because I got tired of seeing makers waste expensive epoxy on guesswork. Art resin is not cheap. A gallon of quality clear epoxy runs anywhere from $50 to $80. Every ounce you waste is money you could have put toward another finished piece that actually sells.
Which Shape Are You Pouring?
The calculator covers three common mold shapes, and picking the right one matters for accuracy.
Rectangle/Tray. This is your workhorse — serving boards, rectangular jewelry trays, resin wall art, tabletops. The calculator uses length × width × depth. Make sure you measure the interior of your mold, not the outer edges. Measure from the deepest part of the cavity. If your tray has a slight slope to the sides, take the depth at the center bottom — that is where your pour will pool deepest.
Circle/Cylinder. Coasters, round pendants, small table tops, clocks, encapsulation domes. The calculator runs on π × radius² × depth. If your mold is 4 inches across, your radius is 2 inches. Simple. I see people enter diameter as radius more than I care to admit — I have done it myself. Double-check that number before you hit calculate.
Coaster Round. This is a fast shortcut for the most common resin project on the planet. The coaster round option is pre-configured to make quick work of coaster pours. If you make coasters in batches for craft fairs or wholesale orders, this shape option alone will pay for itself in saved resin within a few production runs.
Why Your Mix Ratio Is Non-Negotiable
Here is where most beginners mess up. Your resin system has a specific mix ratio — usually printed on the bottle in big letters. Common ratios are 1:1, 2:1, and 3:1 by volume. That first number is your resin. The second is your hardener.
1:1 — Equal parts. Common for clear casting epoxies and deep-pour resins. Easy to remember, but you still need volume accuracy. A 1:1 ratio by volume does not mean "pour until it looks even." It means measure precisely.
2:1 — Two parts resin to one part hardener. Typical for coating and tabletop epoxies. These are often thinner formulas that self-level well. You need more resin because the chemical reaction requires that balance to cure hard and clear.
3:1 — Three parts resin to one part hardener. Common in deep-pour and casting resins that generate less heat during cure. Slower cure times, which means you have more working time but also more time for dust to find your pour.
Custom. Not all resin systems fit a standard ratio. If your brand calls for something unusual — and some industrial epoxies definitely do — use the custom option and enter your specific ratio.
The Resin Volume Calculator handles all of this automatically. You pick your ratio, it divides your total volume accordingly. No mental math. No "I think that looks right." No half-cured sticky messes three days later.
The 5% Buffer — Engineer-Speak for "You Will Spill Some"
Every calculation includes a 5% addition for mixing losses. This was not a random guess. I added it after watching my own pours and realizing that no matter how careful you are, some resin stays in the mixing cup, some coats your stir stick, and some gets trapped in the pour spout. It is the nature of the material.
That 5% is insurance. It means your calculated amount is slightly more than the mold needs, so you do not come up short. And if you mix exactly right and do not spill a drop? You have a tiny leftover puddle you can pour into a small silicone mold to make a cabochon or keychain. Nothing gets wasted.
Always measure from the deepest part of your mold. If your mold cavity is uneven — and many handmade silicone molds are — measure the thickest section. Your calculation is only as good as your measurements.
When You Need This Calculator
You need the Resin Volume Calculator when any of the following is true:
You are making coasters, jewelry trays, serving boards, or encapsulation pieces and you want consistent results batch after batch. One coaster is not the problem. Twelve coasters that all need to match — that is where precision matters. The calculator gets you the same volume every time so your production is repeatable.
You are buying materials for a new project or trying a mold for the first time. Punch the dimensions into the Resin Volume Calculator and you will know exactly how many pours a gallon kit will give you — that is a direct line to knowing your cost per piece for a craft fair. No guessing, no math surprises.
How to Use the Resin Volume Calculator Like a Pro
This calculator has four inputs, and each one changes your result. Here is exactly what to do — and what not to do — for each field.
- Length, Width, and Depth — Measure the interior of your mold — not the outer edges. Use the deepest point of the cavity, especially if your mold has a curved or sloped bottom. A 1/8-inch measuring error in depth can throw your volume off by 15 percent or more on a shallow coaster. Digital calipers are ideal; a ruler with 1/16-inch marks works fine.
- Shape — Pick the shape that matches your mold. Rectangle/Tray is for serving boards, jewelry trays, and rectangular wall art. Circle/Cylinder is for round pendants, clocks, and encapsulation domes. Coaster Round is a fast shortcut for the most common resin project — it assumes standard coaster proportions so you only enter diameter and depth.
- Mix Ratio — Check your resin brand's bottle — the ratio is usually printed in bold. Most craft epoxies are 1:1 by volume (equal parts resin and hardener). Coating epoxies are often 2:1. Deep-pour resins can be 3:1. If you use a custom ratio from an industrial supplier, select Custom and enter your numbers. Using the wrong ratio means a pour that never fully cures.
- Calculate — Click the button and the calculator returns three numbers: resin volume, hardener volume, and total mixed volume. All include the 5% buffer for mixing losses. Write down the resin and hardener numbers separately. Measure each into separate cups first, then combine — never measure them together in the same cup.
Pro tip for batch work: If you are making 12 coasters for a craft fair, calculate one coaster first. Multiply the resin and hardener results by 12. This gives you exact per-piece material cost — essential for pricing your work. The calculator's 5% buffer is already baked in, so do not add extra waste on top of it.
Open the Resin Volume Calculator in a new tab and walk through these steps with your project. After two or three uses you will be able to estimate your material needs before you even type the numbers — but you will still type them anyway because the precision is worth it.
Final Thoughts from Someone Who Has Wasted His Share
I have poured resin in a hot garage in July and a cold basement in January. I have used cheap epoxy and premium art resin. I have made beautiful pieces and I have made garbage. The difference between a great pour and a wasted pour is almost always the same thing — not knowing how much to mix.
The Resin Volume Calculator does not make your art for you. But it takes the cheapest, most preventable mistake off the table. Measure your mold dimensions carefully and let the math do the work so you can focus on making something someone wants to buy or keep.
And for the record, my brother-in-law still has that board with the ugly line through it. He says it has character. I call it a tuition payment.
