Resin calculator — mold volume to A/B mix weights
Enter mold volume, density, waste, and your brand’s A:B weight ratio to see total resin and how much of each part to weigh.
Inputs use metric (ml / g) — common on wax and resin labels worldwide. Results also show fl oz / oz.
Results
Volume with waste: 110 ml (≈ 3.72 fl oz)
Total resin: 121 g (≈ 4.27 oz)
Part A: 60.5 g (≈ 2.13 oz)
Part B: 60.5 g (≈ 2.13 oz)
Formula
Vwaste=V×(1+waste); total=Vwaste×density; A=total×a/(a+b); B=total×b/(a+b)
Worked steps (check these)
- Volume with waste = 100 × (1+0.1) = 110 ml
- Total resin = 110 × 1.1 = 121 g
- Part A = 121 × 1 ÷ (1+1) = 60.5 g
- Part B = 121 × 1 ÷ (1+1) = 60.5 g
Shopping estimates only — follow supplier safety notes and brand ratios.
Wrong A/B ratios cause soft cures and sticky surfaces. Start from volume, add waste, then split by the printed weight ratio.
How to use
- Estimate mold volume in ml
- Set density and waste %
- Enter A and B ratio numbers from the label
- Weigh Part A and Part B as shown
Why this calculator
- Volume → grams with waste
- Splits A and B by weight ratio
- Shows every arithmetic step
Good for
- Coasters
- Jewelry molds
- River-table test pours
Tips
- Mix only what you can pour within pot life.
- Temperature changes viscosity and working time.
- Weigh on a digital scale — cups are not accurate enough.
Examples
| Input | Output | Note |
|---|---|---|
| 100 ml, density 1.1, waste 10%, A:B 1:1 | 121 g total → 60.5 g each | Default worked example |
| Same volume, A:B 2:1 | More Part A than B by weight | Always match the bottle label |
Resin FAQ
- Volume or weight ratio?
- This tool splits by weight ratio after converting volume×density. If your brand is volume-only, convert carefully or weigh cups.
- How much waste?
- 5–15% covers cup cling and overflows. Deep pours or many molds may need more.
- Making candles instead?
- Use Candle wax calculator for wax and FO.