Resin Mold Volume Calculator
Calculate exact resin amounts for any mold shape.
Supports sphere, cylinder, cube, rectangle, cone, pyramid, and custom shapes.
No sign-ups. Instant results.
💡 Tip: Measure with digital calipers for precision. Shop quality silicone molds.
Example calculation
Let's calculate volume for a cylindrical coaster mold:
| Parameter | Value |
|---|---|
| Mold shape | Cylinder (round) |
| Diameter | 100mm (10cm) |
| Height/Depth | 8mm (0.8cm) |
| Add 10% buffer | Yes |
| Resin needed | 69 ml (or 72 grams) |
Formula: π × (50mm)² × 8mm = 62,832 mm³ ÷ 1000 = 62.8ml + 10% buffer = 69ml
Mold volume formulas
Cylinder (round coasters, tumblers)
Formula: π × radius² × height
Example: Diameter 100mm, height 10mm
π × 50² × 10 = 78,540 mm³ = 78.5 ml
Sphere (round balls, ornaments)
Formula: (4/3) × π × radius³
Example: Diameter 60mm
(4/3) × π × 30³ = 113,097 mm³ = 113.1 ml
Cube (square molds)
Formula: side × side × side
Example: 50mm cube
50 × 50 × 50 = 125,000 mm³ = 125 ml
Rectangle / Box (trays, pendants)
Formula: length × width × height
Example: 80mm × 50mm × 15mm
80 × 50 × 15 = 60,000 mm³ = 60 ml
Cone / Pyramid (pointed decorations)
Formula: (1/3) × π × radius² × height
Example: Base diameter 60mm, height 80mm
(1/3) × π × 30² × 80 = 75,398 mm³ = 75.4 ml
Hemisphere (half-sphere domes)
Formula: (2/3) × π × radius³
Example: Diameter 60mm
(2/3) × π × 30³ = 56,549 mm³ = 56.5 ml
Accurate mold measuring tips
📏 Measure the cavity, not the mold
Always measure the inside space where resin goes, not the outside dimensions of the silicone mold itself.
💧 Use water displacement method
For irregular molds, fill with water, pour into a measuring cup. The water volume equals resin volume needed.
🔢 Measure in millimeters
Millimeters provide better accuracy than inches for small molds. 1ml = 1 cubic centimeter = 1,000 cubic mm.
✅ Double-check measurements
Measure twice, especially for expensive resin projects. Being off by 5mm can waste 10-20ml of resin.
🛒 Shop molds: Jewelry Molds • Coaster Molds • Tray Molds
Mold volume calculator FAQs
How do I calculate mold volume for resin?
Measure your mold dimensions (diameter, length, width, height depending on shape), then use the appropriate formula. For a sphere: (4/3) × π × radius³. For a cylinder: π × radius² × height. For a cube or rectangle: length × width × height. Our calculator does the math automatically—just enter your measurements and select your mold shape.
How do I convert ml to grams for resin?
Multiply milliliters by 1.05 to convert to grams. Most epoxy resins have a density of 1.05 g/ml, meaning 100ml of resin weighs approximately 105 grams. This calculator automatically converts between ml, grams, and ounces. When measuring on a digital scale, use grams for the most accuracy.
What if my mold has an irregular shape?
For irregular molds, use the water displacement method: fill the mold with water, pour the water into a measuring cup, and note the volume in ml. This gives you the exact amount of resin needed. Alternatively, measure the longest dimensions and use our Custom shape option with an 85% reduction factor to approximate the volume.
Should I add extra resin to my calculated volume?
Yes, always add 10-15% extra resin. This accounts for waste in mixing cups, resin stuck to stirring tools, and air bubbles you'll pop. Use the buffer checkbox in this calculator to automatically add 10% extra. For small molds under 50ml, this buffer is especially important since being short by even 5ml can mean an incomplete pour.
How do I measure mold dimensions accurately?
Use digital calipers or a ruler to measure the inside cavity of the mold, not the outside dimensions. For round molds, measure diameter across the widest point. For depth, measure from the top edge to the bottom of the cavity. Measuring in millimeters provides the most accuracy—10mm is much more precise than rounding to the nearest 1/4 inch.
Can I reuse resin molds?
Yes, quality silicone molds can be reused 50-100+ times if cared for properly. Use mold release spray for easier demolding, wash with soap and water after each use, and store flat to prevent warping. Avoid sharp tools when demolding—gently flex the mold instead.
What's the difference between volume and weight for resin?
Volume measures space (ml, oz), while weight measures mass (grams, pounds). Resin is measured by weight for mixing accuracy because volume can vary with air bubbles and temperature. However, mold capacity is measured in volume (ml). Use this calculator to convert mold volume to resin weight, then use our Small Batch Mixing Calculator to get Part A and Part B weights.