How Much Epoxy Do I Need? How to Calculate It for Any Pour

Running short in the middle of a pour is the one mistake you cannot fix later. Epoxy cures on its own schedule, so a second batch mixed twenty minutes behind the first will not blend invisibly into it, and a batch mixed the next day is a separate layer with a seam. Ordering too much is a smaller problem, but it is still money sitting on a shelf.

The good news is that the arithmetic is genuinely simple, and we have a tool that does it for you.

Use the Superclear Epoxy Resin Calculator — enter your length, width and depth, pick your formulation, and it returns the volume in cubic inches, fluid ounces and gallons, along with your Part A and Part B split.

This guide covers what the calculator cannot decide for you: which depth you should be typing in, whether your project can legally be poured in one go, and how the number you get maps onto the kit sizes we actually sell. That last part is where most of the money is won or lost.

The Formula, in Two Numbers

Epoxy is sold by volume, and volume is length times width times depth. Measure all three in inches, multiply them together, and you have the volume of your pour in cubic inches:

Length × Width × Depth = cubic inches

From there you only need one of two divisors:

• Cubic inches ÷ 231 = US gallons (231 cubic inches is one US gallon)
• Cubic inches ÷ 1.805 = US fluid ounces

And if you have ounces and want gallons, divide by 128.

Use gallons for anything table-sized and ounces for small work, where a gallon figure like 0.14 tells you nothing useful.

Round and Curved Projects

For a circle, swap the length-times-width step for the area of the circle:

1. Measure the diameter in inches and halve it to get the radius.
2. Radius × Radius × 3.14159 × Depth = cubic inches
3. Divide by 231 for gallons, or by 1.805 for fluid ounces.

An 18-inch round coated at an eighth of an inch works out to 9 × 9 × 3.14159 × 0.125, which is about 31.8 cubic inches, or roughly 17.6 fluid ounces.

For anything genuinely irregular — a live-edge river channel, a free-form art panel — break it into rectangles, work each one out, and add them together. The one measurement that catches people out is a river channel that bulges in the middle. Measure it in three or four places and use the average width, not the narrowest point. A single measurement taken at the waist of the channel will cost you real money.

The Number Is Only Half the Answer

Here is the part a calculator cannot do. It will happily tell you that a slab needs four gallons at three inches deep, and it will be arithmetically correct — but whether you can actually pour those four gallons in one go depends entirely on which product is in the bucket.

Every Superclear formulation has a maximum depth per pour, and they are not close to each other:

So the sequence is: work out your volume, then check it against the depth ceiling of the product you intend to use, and only then decide how many pours you are making. If your total depth exceeds what the product can do in one application, you are pouring in layers — and each layer needs its own calculation, its own mixed batch, and its own recoat timing.

Deep Pour is the casting resin, built to fill a void. Table Top is a coating, built to go over a surface. They are not interchangeable, and if you are unsure which one your project needs, we compare them side by side here. For the full detail on depth limits and why they exist, see how deep you can pour epoxy in one layer.

The Depth You Type In Is the Expensive Decision

If you take one thing from this page, take this. For a coating, the depth that belongs in the calculator is the thickness the resin actually settles at — not the maximum the product can handle.

Countertop Epoxy is the clearest example. It can be poured up to a quarter inch per pour, but it self-levels at a much thinner depth, typically 1/32 to 1/16 of an inch, depending on temperature and volume. Those two numbers produce wildly different orders.

Take an eight-foot kitchen run, 96 inches by 25 inches:

• At 1/16 inch, the self-levelling thickness: 96 × 25 × 0.0625 = 150 cubic inches, or about 0.65 gallons.
• At 1/4 inch, the maximum: 96 × 25 × 0.25 = 600 cubic inches, or about 2.6 gallons.

That is four times the resin for the same countertop. With ten percent added for waste, the first comes to roughly 0.71 gallons and comfortably fits a 1.5 Gallon Kit at $169.99. The second comes to about 2.86 gallons and pushes you into the 3 Gallon Kit at $289.99. Typing the wrong depth into a perfectly good calculator is a $120 mistake before you have opened a bottle.

The same logic applies to Table Top. A flood coat over a bar top is usually a thin film, not a quarter-inch slab, and you should be calculating the film. Castings are the opposite: for a river table or a deep cast, the depth in the formula is the real, finished depth of the void, because you genuinely are filling it to that level.

Always Add Some Overage

Whatever number you land on, add about ten percent.

That covers the material that stays behind on the sides of the mixing container, the amount you lose transferring between buckets, and the small variations in a slab that is not perfectly flat. It also covers the far more common problem of a channel or a form being slightly larger than it measured.

Our own mixing instructions are explicit that you should not scrape the container when you pour, precisely because the unmixed material clinging to the sides and bottom is what causes soft and tacky spots. That resin is deliberately sacrificed. Build it into your number rather than discovering it at the bottom of the bucket.

It is always better to have epoxy left over than to be short.

Mix Size Has Its Own Limit

Ordering enough is one problem. Mixing it is another, and they have different answers.

Table Top Epoxy and Designer Art Resin are mass sensitive: the larger the batch, the more heat it generates and the shorter your working time becomes. Our directions recommend mixing a maximum of 2 quarts of total volume at a time at 74°F, and never more than half a gallon in a single container. In a warmer shop, mixing above 2 quarts will restrict your working time severely.

So a bar top that needs a gallon is not one gallon-sized mix. It is a series of smaller batches, poured and spread as you go. That is by design, and the directions spell out why it works: once you spread the first batch across the surface, the mass is no longer concentrated, and you have plenty of time to mix the next one.

Deep Pour behaves differently because it is formulated for mass, but it still has a mixing rule — if you are stirring by hand with a stick rather than a drill mixer, do not mix more than a quart at a time.

Plan the pour, not just the purchase.

Volume or Weight?

The calculators give you a volume, and for most projects measuring by volume is the right call — it involves less maths and leaves less room for error.

If you prefer to measure by weight, the ratios are different from the volume ratios and are specific to each formulation:

The reason the weight ratios are not the same as the volume ratios is that resin and curing agent have different densities. Whichever method you choose, be exact and stay with it for the whole project — an approximate ratio is the most reliable way to end up with a surface that never fully hardens.

Two Worked Examples

A river table. A channel 60 inches long, averaging 5 inches wide, poured 1.5 inches deep: 60 × 5 × 1.5 = 450 cubic inches. Divided by 231, that is 1.95 gallons; with ten percent overage, call it 2.15.

Now map it onto real kits. A 1.5 Gallon Kit ($169.99) plus a 0.75 Gallon Kit ($99.99) gets you 2.25 gallons for $269.98. The single 3 Gallon Kit is $239.99 — more resin, less money. It is always worth checking the next size up before you combine two smaller kits.

Remember that a river table needs a little Table Top as well. Our Deep Pour directions call for sealing the wood with Table Top first and pouring the deep pour while that seal coat is still tacky. Bare wood outgasses into a deep pour if you skip it. If you are building one, our river table guide goes through the whole sequence.

A bar top. A 60 by 20 inch surface finished at an eighth of an inch: 60 × 20 × 0.125 = 150 cubic inches, or about 0.65 gallons, which is roughly 0.71 with overage — comfortably inside a 1 Gallon Kit at $64.99.

But a coating job is rarely one pass. A seal coat goes on first, then the flood coat, and each is its own mixed batch with its own volume. Work out how many coats you are actually doing before you order — we cover how many coats a table top needs here.

Buying for the Project You Have

Once you know your number, the kit ladder is straightforward. Liquid Glass Deep Pour runs from a 48oz Kit at $49.99 through 0.75, 1.5 and 3 Gallon Kits at $99.99, $169.99 and $239.99, with bulk kits from 9 to 21 gallons for shop work. Table Top runs from a 1 Pint Kit at $29.99 up to a 2 Gallon Kit at $114.99, with bulk kits beyond that.

Two habits are worth forming. Round up to the next kit rather than down — the gap between a finished table and a ruined one is often a few ounces. And check whether a single larger kit costs less than two smaller ones, because on our ladder it frequently does.

If your project is unusual enough that the arithmetic here does not obviously fit it, call us on 888-849-0588 or email superclear@fgci.com and we will work the number out with you. We would much rather spend five minutes on the phone than have you short in the middle of a pour.

Frequently Asked Questions

How much epoxy do I need?

Multiply your project's length by its width by your intended depth, all in inches, then divide by 231 for gallons or by 1.805 for fluid ounces, and add about ten percent for waste. For round projects, use radius × radius × 3.14159 × depth instead. The Superclear Epoxy Resin Calculator does all of this for you.

How many cubic inches are in a gallon of epoxy?

231 cubic inches make one US gallon, and one US fluid ounce is about 1.805 cubic inches. Those two numbers are all you need to convert a measured volume into an order.

What depth should I use in the calculator?

For a casting such as a river table, use the real finished depth of the void. For a coating, use the thickness the resin settles at rather than the product's maximum — Countertop Epoxy, for instance, self-levels at roughly 1/32 to 1/16 of an inch even though it can be poured up to a quarter inch. Using the maximum instead of the self-levelling thickness can multiply your order several times over.

What happens if I mix too much at once?

Table Top Epoxy and Designer Art Resin are mass sensitive, so a large batch heats up and your working time shortens sharply. Mix a maximum of 2 quarts of total volume at a time at 74°F, and never more than half a gallon in a single container. Pour and spread each batch before mixing the next.

Can I pour my whole project in one go?

Only if your total depth is within the product's maximum per pour. Liquid Glass Deep Pour handles up to 4 inches in a single application depending on ambient temperature and total mass; the 24 Hour formulation takes 1 inch per layer; Table Top, Countertop and Designer Art Resin are coatings at a quarter inch per pour. Anything deeper is poured in layers.

Should I measure by volume or by weight?

Volume is simpler and is what the calculator returns. If you measure by weight, use the ratio for your specific product — 100:44 for Liquid Glass Deep Pour, 100:43 for the 24 Hour, 100:45 for Countertop, and 100:83 for Table Top and Designer Art Resin. Do not mix the two methods within a project.

How long before I can use what I poured?

Superclear epoxies cure hard to the touch in about 24 hours, and Deep Pour castings can generally be demoulded from around 48 hours. Full cure and maximum hardness are reached at 30 days — demoulding is not the same thing as fully cured, so treat a fresh piece gently until then.

Get Your Number First

Measure carefully, pick your depth honestly, check it against the product's limit, add ten percent, and buy the kit that covers it. That sequence takes two minutes and saves the pour.

Start with the Epoxy Resin Calculator, then pick your resin: Liquid Glass Deep Pour for filling a void, Table Top Epoxy for coating a surface.