How much resin for a 12 × 8 in tray mold?
You need about 21.9 fluid ounces (649 milliliters) of mixed resin to fill a 12 × 8 in tray mold 3/8 inch deep, including 10% extra — 11 fluid ounces each of resin and hardener for a 1:1 kit, or about 24 ounces on a scale.
How to work it out
- 12 in × 8 in × 3/8 in = 36 cu in = 19.9 fl oz
- + 10% = 21.9 fl oz (≈ 24 oz on a scale)
- Mix ratio 1 : 1 by volume, SG A 1.15 / B 0.95 (typical, not published by the maker — type your data sheet’s SGs for exact weights) → Part A 11 fl oz (13.2 oz) + Part B 11 fl oz (10.9 oz)
Serving and rolling trays are usually shallow — 1/4 to 1/2 in of resin — with a raised lip molded in. Measure the inside floor of the mold and the depth you’ll fill to; if the tray has handles or a thick rim, the water method will be more accurate than a box estimate.
Adjust for your project
More options: waste · ratio · SG A …
- Per piece (no waste)
- 19.9 fl oz (590 ml)
- Per piece on a kitchen scale (pour to this)
- 21.8 oz (619 g)
- Whole batch by weight, incl. waste (kitchen scale)
- 24 oz (681 g)
- Kits to buy
- 1 kit
- When mixing — Part A (resin)
- 11 fl oz (324 ml)
- When mixing — Part B (hardener)
- 11 fl oz (324 ml)
- Part A by weight
- 13.2 oz (373 g)
- Part B by weight
- 10.9 oz (308 g)
- Left over from the last kit
- 10.1 fl oz (297 ml)
- What to buy: 1 × 32 fl oz casting resin kit. Each kit has both bottles (resin + hardener) — you don’t buy them separately. Looking at a different kit size? Change Kit size above.
Resin for a 12 × 8 in tray mold, by fill depth
| Fill depth | Casting resin to buy | Whole batch by weight, incl. waste (kitchen scale) | Kits to buy |
|---|---|---|---|
| 1/4 in | 14.6 fl oz | 16 oz | 1 kit |
| 3/8 in | 21.9 fl oz | 24 oz | 1 kit |
| 1/2 in | 29.3 fl oz | 32 oz | 1 kit |
| 3/4 in | 43.9 fl oz | 48.1 oz | 2 kits |
What to know about a 12 × 8 in tray mold
Pick the resin for the depth. At 3/8 in, a tray is thicker than most coating (tabletop) epoxies allow in one pour — many cap a single layer at 1/4 in — but far thinner than a deep-pour resin is designed for. MAS, for example, rates its Deep Pour X for 2–3 in pours and warns that pours under 2 in can take 48–72 hours to cure. A casting resin rated for about 1/2 in is the easy middle ground; with a coating epoxy, pour two layers of 3/16 in.
Support the mold before you fill it. A flexible silicone tray mold full of about 24 oz (1.5 lb) of liquid resin will sag if you pick it up or leave it over a gap, and the tray comes out thicker in the middle. Set it on a flat, level board first and carry the board, not the mold. Fill to the depth line you planned, not the top of the mold’s rim — the rim is often taller than the tray is meant to be.
A 32 fl oz kit covers one tray with about 10 fl oz spare, which is enough for a set of coasters from the same batch if you have the molds ready. Two trays at once need a second kit. Made the silicone mold yourself? The rubber side of the job is worked out in how much silicone for a 12×8 tray mold. For something much smaller, compare how much resin for 12 pendant molds, where the water method replaces a ruler entirely.
Different size? Use the full Resin Mold Calculator.
What you’ll need
- Casting resin for molds & coastersMid-range price
Thinner and slower than coating resin, so it fills mold detail and handles thicker pours — check the label’s maximum depth.
See options on Amazon (opens in a new tab) - Silicone coaster & tray moldsBudget price
Flexible molds release cured resin without mold release. Measure the inside to calculate volume.
See options on Amazon (opens in a new tab) - Digital scale (0.1 g)Budget price
For mixing by weight. Far more accurate than cup lines for small batches — and it doubles for the water method on molds.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How much resin for a 12x8 tray mold at 1/4 inch deep?
About 14.6 fluid ounces of mixed resin with 10% extra — 16 oz on a scale.
How much resin for a 12x8 tray mold at 1/2 inch deep?
About 29.3 fluid ounces with 10% extra, which still fits one 32 fl oz kit — but only just, with 2.74 fl oz to spare.
How much resin to pour two 12x8 trays?
About 43.9 fluid ounces for both at 3/8 in deep — 2 kits of 32 fl oz.
Other common sizes
Sources
- Smooth-On — How much mold rubber do I need? (opens in a new tab) — The water method: fill the mold or containment with water to measure the volume a material has to fill
- MAS Epoxies — Deep Pour X casting resin (opens in a new tab) — Deep-pour resin for 2–3 in pours; thin pours under 2 in can take 48–72 h to cure
- Epoxyworks — The Basics of WEST SYSTEM Epoxy Resin and Hardener (opens in a new tab) — Warmer resin cures faster (every 18°F above 72°F roughly halves cure time); mass and shape change how fast a batch heats up