Resin mold chart
What every common mold actually holds, worked out from its dimensions rather than taken from a listing, with the Shore hardness and the resin each one needs, which are the two things no seller prints.
INPUTS
Every mold below, with what a cavity actually holds worked out from its dimensions rather than taken from a
listing.
The filter listings do not offer. Buying a mold your resin cannot fill in one go is the commonest mismatch in
the craft, and it usually arrives inside a beginner kit.
%
Applied to the "mix this much" column. You cannot go back for more once a pour has started, so every figure in
that column is deliberately long.
A mold does not make a depth safe. Where the chart says a mold needs several lifts, that is a thermal limit of
the resin rather than a finish preference, and silicone insulates, so a deep cavity holds the heat in rather
than letting it out.
RESULTS
Round coaster mold, 4 cavities, one cavity holds
78.5 ml
346 ml to fill all 4 Deep pour Shore 30A
The chart
| Mold | Cavities | One holds | Mix this much | Depth | Needs | Pours | Silicone |
|---|---|---|---|---|---|---|---|
| Round coaster mold, 4 cavities | 4 | 78.5 ml | 346 ml | 3/8 in | Deep pour | 1 | Medium, the usual compromise |
| Square coaster mold, 6 cavities | 6 | 100.0 ml | 660 ml | 3/8 in | Deep pour | 1 | Medium, the usual compromise |
| Serving tray mold with handles | 1 | 480.0 ml | 528 ml | 5/16 in | Deep pour | 1 | Medium, the usual compromise |
| Pendant and bezel mold, 12 cavities | 12 | 3.0 ml | 40 ml | 1/8 in | UV | 1 | Soft, easy release, flexes under weight |
| Bangle mold, 3 sizes | 3 | 14.0 ml | 46 ml | 3/8 in | Deep pour | 1 | Soft, easy release, flexes under weight |
| Sphere mold, 6 cavities | 6 | 33.5 ml | 221 ml | 1 9/16 in | Deep pour | 1 | Medium, the usual compromise |
| Pyramid and cube molds, mixed | 4 | 60.0 ml | 264 ml | 2 3/8 in | Deep pour | 2 | Medium, the usual compromise |
| Deep casting block mold | 1 | 900.0 ml | 990 ml | 2 3/8 in | Deep pour | 2 | Firm, holds edges, fights on release |
| Flat sheet mold, for cutting | 1 | 180.0 ml | 198 ml | 1/8 in | Table top | 1 | Medium, the usual compromise |
The commonest first mold and the one most people underestimate: at 10 mm a coaster is a casting, not a coating, so it wants a deep pour resin rather than the table top epoxy in the same kit.
Depth in one lift
2 inof deep pour
This mold needs
1pour
Every volume here is worked out from the mold's own dimensions, not taken from a listing, which is why a square
cavity comes out about a quarter above a round one of the same width, and why a set of six runs short on a batch
sized for four. The Shore figure is the other one nobody prints: soft silicone releases an undercut and sags under
a heavy pour, firm silicone holds an edge and fights you on the way out.
Free printable
Print the pour-depth card
Maximum pour depth and cure windows by resin type, the number that cracks a casting. Free.
How this is worked out
Every volume on this chart is worked out from the mold's own dimensions through the same function the epoxy calculator uses, a cavity's width, depth and geometry, never a figure copied from a listing. That is deliberate: "large" varies between suppliers and 100 mm across by 10 mm deep does not. One cavity is its shape's area at its depth; the full-mold figure is that times the cavity count; and the "mix this much" column adds the wastage allowance on top, because a mold cannot be topped up once the pour has started. The last two columns are the ones no listing carries. The resin each mold needs comes from its own depth against each system's ceiling, 1/8 in for table top / coating epoxy, 2 in for deep pour / casting epoxy, 3 mm a layer for UV resin, and the Shore A figure is banded into what it means in the hand rather than left as a number.
cavity = its own geometry at its own depth never a quoted figure
full = cavity × cavities
mix = full × (1 + wastage) 10% by default
lifts = ceil(depth ÷ the system's ceiling)
square vs round, same width: +27%
100 mm coaster → 79 ml a cavity, 346 ml for all 4
Questions makers ask
How much resin does a coaster mold hold?
A 100 mm round cavity 10 mm deep holds 79 ml, so filling all 4 takes 314 ml, 346 ml once the 10% that stays in the cup is added. That is the figure to mix, and it is what almost every listing declines to tell you.
Do square molds hold more than round ones?
About 27% more at the same width and depth, because a circle inscribed in a square loses the corners. Square coaster mold, 6 cavities against Round coaster mold, 4 cavities is 100 ml a cavity against 79 ml. It sounds like a detail and it is exactly how a batch mixed for one set runs short on the other.
What resin do I use for a coaster mold?
Deep pour / casting epoxy, at that depth. The commonest first mold and the one most people underestimate: at 10 mm a coaster is a casting, not a coating, so it wants a deep pour resin rather than the table top epoxy in the same kit. Only 2 of the 9 molds on this chart can be filled in one go with table top / coating epoxy, its ceiling is 1/8 in per pour, and everything else is several coats or the wrong resin. <a href="/deep-pour-vs-table-top-epoxy">The difference between the two</a> is a heat limit, not a finish preference.
What Shore hardness should a resin mold be?
Soft for anything with an undercut and firm for anything that has to keep its edges. Pendant and bezel mold, 12 cavities is Shore 25A, soft, easy release, flexes under weight, because a cured pendant has to flex out. Deep casting block mold is Shore 40A, firm, holds edges, fights on release, because a soft mold that size sags in the middle and casts something that rocks. It is the figure listings never print, and it decides more about the result than the price does.
Why does my mold cast a matt piece?
Because the mold surface is matt, and a casting takes the finish of whatever it was cast against. A glossy mold gives a clear piece straight out; a matt one has to be sanded through the grits and polished back, which is hours of work per piece. It is the single biggest quality difference between a cheap mold and a good one, and it is almost never in the listing.
How much resin for a tray mold?
480 ml for the 300 × 200 mm tray at 8 mm. The largest single-cavity mold most makers own, and the one where running short mid-pour is unrecoverable. Firmer silicone here matters, a soft tray mold sags in the middle and casts a tray that rocks.
Which molds work with UV resin?
Only the shallow ones. UV resin cures 3 mm per layer at most, because the resin absorbs the light that sets it, so the pendant and bezel mold, 12 cavities at 3 mm is right for it and a 10 mm coaster is four layers of patience. <a href="/uv-resin">The UV guide</a> covers where the line falls.
How many castings does a mold give?
Roughly a hundred before it clouds and starts losing detail, which is the number to divide its price by when you cost a piece, <a href="/resin/pricing-calculator">the pricing calculator</a> does exactly that. If the shape you want is not on any chart, <a href="/resin/silicone-mold-calculator">pouring your own</a> is the other half of this question.
The categories, and what goes wrong in each
Molds group by what they are for rather than by size, and each group fails in its own way. The volume range is what a full mold takes, before wastage.
| Category | On this chart | A full mold takes | Usually wants |
|---|---|---|---|
| Coasters | 2 | 314 ml – 600 ml | Deep pour |
| Trays | 1 | 480 ml | Deep pour |
| Jewelry | 2 | 36 ml – 42 ml | UV |
| Spheres, cubes and pyramids | 2 | 201 ml – 240 ml | Deep pour |
| Deep casting blocks | 1 | 900 ml | Deep pour |
| Flat sheets | 1 | 180 ml | Table top |
The one row worth reading twice is the sheet mold at 3 mm. It is the only mold here a coating epoxy fills in one pour, and casting a sheet and cutting shapes out of it afterwards is the cheapest route to a lot of small flat pieces, no cavity, no release problem and no second lift.
Read before your next batch
- How to make resin art Buy the right resin for the depth you are pouring, weigh both parts rather than eyeballing them, and leave it alone once it is poured. Almost every first-batch failure is one of those three.
- UV resin One part, no hardener, no measuring, and set in about a minute. It is a genuinely different product from two-part epoxy, and its limits are not the ones you would guess.
- Resin vs epoxy: which type to buy Four products share the word, and the one thing that separates them is how deep you can pour them. Pick by that, and everything else follows.
- Deep pour vs table top epoxy Two clear liquids that look identical in the bottle, with maximum pour depths about ten times apart. Going past the wrong one is a heat problem, not a patience problem.