How much resin for 12 jewelry and pendant molds?
You need about 66 milliliters of mixed resin to fill twelve pendant molds that each hold 5 g of water, including 10% extra — 33 milliliters each of resin and hardener for a 1:1 product, or about 69.3 grams on a scale.
How to work it out
- 5 g of water ≈ 5 ml
- × 12 + 10% = 66 ml (≈ 69.3 g 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 33 ml (38 g) + Part B 33 ml (31.4 g)
Small jewelry molds are too detailed to measure with a ruler, and their volumes are tiny — many pendant cavities hold only a few milliliters. Fill one with water on a 0.1 g scale and you’ll know within a fraction of a milliliter. Change the water weight in the calculator to match your own mold.
Adjust for your project
More options: waste · ratio · SG A …
- Per piece (no waste)
- 5 ml (0.17 fl oz)
- Per piece on a kitchen scale (pour to this)
- 5.25 g
- Whole batch by weight, incl. waste (kitchen scale)
- 69.3 g
- Kits to buy
- 1 kit
- When mixing — Part A (resin)
- 33 ml (1.12 fl oz)
- When mixing — Part B (hardener)
- 33 ml (1.12 fl oz)
- Part A by weight
- 38 g (1.34 oz)
- Part B by weight
- 31.4 g (1.11 oz)
- Left over from the last kit
- 184 ml (6.22 fl oz)
- What to buy: 1 × 250 ml 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 12 pendants, by how much water one cavity holds
| Water per cavity | Casting resin to buy | Whole batch by weight, incl. waste (kitchen scale) |
|---|---|---|
| 2 g | 26.4 ml | 27.7 g |
| 3 g | 39.6 ml | 41.6 g |
| 5 g | 66 ml | 69.3 g |
| 8 g | 106 ml | 111 g |
| 12 g | 158 ml | 166 g |
What to know about casting a dozen pendants
Mix one batch for the whole tray, not one per pendant. A single cavity takes only about 5 ml, and most epoxies list a minimum batch size on the label because a few milliliters is almost impossible to measure on-ratio — an error of half a milliliter is a 10% mistake. Sixty-odd milliliters split between two cups is easy to weigh on a 0.1 g scale; check whether your kit gives a weight ratio, because 1:1 by volume is not always 1:1 by weight.
Expect small castings to cure slowly. A thimble of resin can’t build up much heat, so pendants often stay soft longer than the label’s times, which are usually measured on a bigger mass. Keep the room warm and steady — Epoxyworks puts the effect at roughly double the cure time for every 18°F (10°C) cooler — and wait the full time before demolding thin bails or points that snap easily.
Most of the 10% extra goes on doming. Fill each cavity slightly proud so surface tension rounds the back, and pop surface bubbles with a toothpick or a quick pass of a heat gun. Dried flowers, glitter and foil take up some of the cavity; for anything bulkier, enter its volume per piece. A 250 ml kit leaves about 184 ml after this batch — plenty for several more sets, or for a shallow dish like the one in how much resin for a 12×8 tray mold.
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) - 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) - Graduated mixing cups & stir sticksBudget price
Small cups marked in ounces and ml for art, coasters and tumblers. Use a fresh cup when you transfer to a second container.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How much resin for 24 pendant molds of 5 ml each?
About 132 milliliters with 10% extra — 139 g on a scale, still inside one 250 ml kit.
How much resin for 12 small charm molds that hold 3 g of water?
About 39.6 milliliters for all twelve, including 10% extra.
How much resin for 12 large pendant molds that hold 8 g of water?
About 106 milliliters (111 g by weight), including 10% extra.
Other common sizes
- How much resin for a 12×8 tray mold — 21.9 fl oz
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