Silicone Mold Resin Calculator
Silicone molds come in hundreds of shapes and sizes. This guide gives you pre-calculated resin volumes for the most popular mold types — coasters, cubes, cylinders, domes, and trays — plus the formula to calculate any mold you have on hand.
Use the free calculator for a precise resin estimate for any mold shape.
Calculate Resin Amount →Universal Conversion Formula
mL of resin = mold volume (cubic cm) × 1.0 (approx — resin density ≈ 1 g/mL)
All the tables below use this formula. For metric molds, measure in centimeters: the mold's internal volume in cm³ equals approximately the number of mL of resin you need.
Coaster Molds
Round Coaster Molds (1/4 inch / 6mm depth)
| Diameter | Per Coaster | Set of 4 | Set of 6 |
|---|---|---|---|
| 3.5 in | 5.4 fl oz (160 mL) | 21.5 fl oz | 32 fl oz |
| 4 in | 7.0 fl oz (207 mL) | 28 fl oz | 42 fl oz |
| 4.5 in | 8.8 fl oz (261 mL) | 35 fl oz | 53 fl oz |
| 5 in | 10.9 fl oz (322 mL) | 43.5 fl oz | 65 fl oz |
Square Coaster Molds (1/4 inch depth)
| Size | Per Coaster | Set of 4 | Set of 6 |
|---|---|---|---|
| 3.5 × 3.5 in | 6.7 fl oz (199 mL) | 27 fl oz | 40 fl oz |
| 4 × 4 in | 8.9 fl oz (263 mL) | 35.5 fl oz | 53 fl oz |
| 4.5 × 4.5 in | 11.3 fl oz (333 mL) | 45 fl oz | 68 fl oz |
Cube & Block Molds
| Cube Size | Resin per Piece | In mL |
|---|---|---|
| 1 × 1 × 1 in | 0.55 fl oz | 16 mL |
| 1.5 × 1.5 × 1.5 in | 1.9 fl oz | 56 mL |
| 2 × 2 × 2 in | 4.4 fl oz | 130 mL |
| 3 × 3 × 3 in | 15 fl oz | 443 mL |
| 4 × 4 × 4 in | 35.5 fl oz | 1,050 mL |
Dome & Hemisphere Molds
| Dome Diameter | Resin per Dome | In mL |
|---|---|---|
| 2 in | 1.2 fl oz | 34 mL |
| 3 in | 3.9 fl oz | 115 mL |
| 4 in | 9.3 fl oz | 275 mL |
| 5 in | 18.1 fl oz | 535 mL |
| 6 in | 31.3 fl oz | 926 mL |
Tray & Geode Molds
| Mold Size (L × W × D) | Resin Needed | In mL |
|---|---|---|
| 6 × 4 × 0.5 in (small tray) | 6.6 fl oz | 196 mL |
| 8 × 5 × 0.5 in | 11.1 fl oz | 328 mL |
| 10 × 7 × 0.75 in (medium tray) | 29.2 fl oz | 864 mL |
| 12 × 8 × 0.75 in | 40 fl oz | 1,183 mL |
| 12 × 9 × 1 in (large geode) | 60 fl oz | 1,774 mL |
Tips for Silicone Mold Casting
- No release agent needed: Silicone is naturally non-stick. Clean and dry the mold before each use.
- Add 5–10% extra: Always mix slightly more than your calculated volume to account for cup residue and mixing losses.
- Support floppy molds: Place flexible silicone molds inside a cardboard box or on a flat board before pouring so they hold their shape.
- Demold time: Wait the full cure time listed on your resin (usually 24–48 hours) before demolding. Early removal causes distortion.
- Deep molds: If your mold is deeper than 1 inch, use a casting resin with a higher heat tolerance or pour in layers to prevent exothermic overheating.
Frequently Asked Questions
How much resin do I need for a coaster mold?
A standard 4-inch round coaster mold at 1/4 inch depth needs approximately 7 fl oz of resin. A set of 4 coasters needs about 28 fl oz (just under 1 quart). Add 10% extra for mixing losses.
Do you need a release agent for silicone molds?
No — silicone is naturally non-stick. Resin releases cleanly without any release agent. For plastic or wood molds, apply mold release or petroleum jelly first.
Why is my resin sticking to the silicone mold?
Resin sticks to silicone molds when removed too early before full cure. Let the resin cure at least 24 hours before demolding. Flex the silicone to release the piece. If the resin is still tacky, it hasn't cured — check your mix ratio and temperature.