Tools I built because I needed them.
Free to use.
A growing collection of calculators and reference tools for studio potters. Each one addresses a specific problem that comes up at the wheel or in the studio: material estimation, shrinkage, firing, glaze volume. Built for the kind of work that deserves better tools, and shared here for anyone who needs them.
Pottery Clay & Shrinkage Calculator
Planning a ceramic piece often involves a fair amount of guesswork. How much clay do you need? How large should you throw it to account for shrinkage? What will the final dimensions be after drying and firing?
This free pottery calculator helps answer those questions before you start.
Designed for wheel throwers and hand-builders alike, it estimates clay requirements, compensates for clay body shrinkage, and predicts finished dimensions based on your target size. Whether you're making mugs, bowls, plates, vases, or custom forms, it provides quick, practical calculations that can save time, reduce waste, and improve consistency across your work.
Use it to:
• Estimate the amount of clay needed for a piece before throwing or hand-building.
• Calculate drying and firing shrinkage.
• Determine the dimensions required to achieve a desired finished size.
• Plan production runs with greater consistency.
• Reduce material waste and failed size estimates.
• Access the built-in Reference Tab, containing typical clay weights and dimensions for common pottery forms.
All calculations are based on commonly accepted pottery volume and shrinkage formulas and should be treated as practical estimates. Actual results will vary depending on clay body, wall thickness, trimming, and firing conditions.
Clay Calculator by Varadero Studio
Add 15–20% extra for trimming waste and centering losses.
Typical ranges — values vary by manufacturer and firing temperature. Always test your specific clay with test tiles.
| Clay body | Bisque | Total (wet → fired) | Cone |
|---|---|---|---|
| Earthenware | 4–6% | 8–12% | 04–1 |
| Stoneware | 5–7% | 10–15% | 6–10 |
| Porcelain | 6–8% | 12–20% | 6–12 |
| Raku | 3–5% | 8–12% | 06–08 |
| Paper clay | 4–6% | 10–16% | varies |
| Terracotta | 4–5% | 8–11% | 04–2 |
| Form | Typical clay | Notes |
|---|---|---|
| Espresso cup | 150–200 g | ~6–7 cm tall |
| Mug | 300–500 g | ~10 cm tall |
| Cereal bowl | 400–600 g | ~8 cm tall |
| Serving bowl | 700–1000 g | ~12 cm tall |
| Dinner plate | 600–900 g | ~26–28 cm diam. |
| Bud vase | 300–500 g | ~18 cm tall |
| Floor vase | 1500–3000 g | 35 cm+ tall |