Clay Weight Calculator
Clay is modelled by volume and sold by weight. Polymer clay runs about 1.7 g/cm³, so a 60 cm³ piece takes 102 g — two of the standard 57 g blocks. Air-dry clay is lighter, 1.2–1.5, so the same volume weighs less, but it loses water as it dries and shrinks by over 10%, which you have to build in.
Your numbers
Clay needed
102g
Count
2
Formula
Clay needed = Model volume × Clay density
Filling the core with aluminium foil cuts the clay weight by more than half — and thick polymer clay does not cure evenly all the way through, so it cracks as it cools. Big pieces get an armature to stop the cracking, not just to save clay. Block weights vary by brand: Fimo 57 g, Fimo Professional 85 g.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Model volume (cm³)The volume of the model you are moulding. | 60 | 0.1 and up |
| Clay density (g/cm³)Grams per cm³ — polymer near 1.7, air-dry lighter. | 1.7 | 0.4 ~ 2.5 |
Step by step
Quick reference table
Results when only Model volume (cm³) changes and everything else stays put.
| Model volume (cm³) | Clay needed (g) | Count |
|---|---|---|
| 30 | 51 | 1 |
| 45 | 77 | 2 |
| 60 | 102 | 2 |
| 90 | 153 | 3 |
| 120 | 204 | 4 |
What each result means
| Result | At default values |
|---|---|
| Clay needed (g)Clay needed by weight, before any loss in baking. | 102 |
| CountA plain count of items; it often ends up as the denominator. | 2 |
Common mistakes
Filling the core with aluminium foil cuts the clay weight by more than half — and thick polymer clay does not cure evenly all the way through, so it cracks as it cools. Big pieces get an armature to stop the cracking, not just to save clay. Block weights vary by brand: Fimo 57 g, Fimo Professional 85 g.
Glossary
- Model volume
- The volume of the model you are moulding.
- Clay density
- Grams per cm³ — polymer near 1.7, air-dry lighter.
- Clay needed
- Clay needed by weight, before any loss in baking.
- Count
- A plain count of items; it often ends up as the denominator.
Frequently asked questions
Q. How is Clay Weight Calculator calculated?
Clay needed = Model volume × Clay density — Clay is modelled by volume and sold by weight. Polymer clay runs about 1.7 g/cm³, so a 60 cm³ piece takes 102 g — two of the standard 57 g blocks. Air-dry clay is lighter, 1.2–1.5, so the same volume weighs less, but it loses water as it dries and shrinks by over 10%, which you have to build in.
Q. Can you walk through an example?
With Model volume 60cm³, Clay density 1.7g/cm³, the answer is Clay needed 102g.
Q. What do I need to enter?
Enter Model volume, Clay density. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Model volume (cm³) moves the answer to Model volume (cm³) 30 → Clay needed (g) 51 and Model volume (cm³) 120 → Clay needed (g) 204. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Filling the core with aluminium foil cuts the clay weight by more than half — and thick polymer clay does not cure evenly all the way through, so it cracks as it cools. Big pieces get an armature to stop the cracking, not just to save clay. Block weights vary by brand: Fimo 57 g, Fimo Professional 85 g.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.