Clay Shrinkage Calculator (Get Your Pre-Fire Dimensions Right)

Q: Do I measure before or after drying?

You always enter your finished (post-firing) dimensions. The calculator figures out how big to make your piece before drying and firing to hit that final size.

Q: Can I use this for slabs or handbuilt pieces?

Yes. Whether you’re slab-rolling, coil-building, or pinching, just enter your final height, width, and depth. The calculator does the rest.

Q: Is this accurate enough for commissions or selling work?

For most pieces, yes. But for critical fits like lids or commissions test your clay’s actual shrinkage or use manufacturer data to be extra sure.

Q: Can I use this calculator for raku or low-fire projects?

Yes but raku shrinkage varies depending on clay and firing method. It’s smart to test your specific setup with sample tiles before final pieces.

Table of Contents

Ever pulled a piece from the kiln and realized it shrunk more than your patience on glaze day? This calculator fixes that. Just pop in your desired finished dimensions, pick your clay type, and I’ll tell you exactly how big to start.

Whether you’re handbuilding a lid or throwing a mug that has to fit that coaster, this tool makes sure your pots come out true to size no surprises, no guesswork.

Clay Shrinkage Calculator

Choose your clay type, enter your desired finished dimensions, and we’ll tell you how large to start.

📐 Clay Shrinkage Explained

H2: How Much Will My Clay Shrink?
Short answers for common types:

Porcelain: ~12–15% own tests to determine the exact amount of shrinkage for your particular clay and firing conditions.
Earthenware: ~5–8%
Stoneware: ~10–13%

“These aren’t gospel, folks just the ballpark based on what I’ve tested over the years. Your clay brand and kiln might dance to a different tune.” – Ed

❓ Clay Shrinkage Calculator FAQs

Do I measure before or after drying?

You always enter your finished (post-firing) dimensions. The calculator figures out how big to make your piece before drying and firing to hit that final size.

What if I don’t know my clay’s shrinkage rate?

No worries. Just choose your clay type earthenware, stoneware, or porcelain and we’ll use an average rate based on real-world use. It’s not lab-perfect, but it gets you in the ballpark.

Can I use this for slabs or handbuilt pieces?

Absolutely. Whether you’re slab-rolling, coil-building, or pinching, this calculator works. Just enter the final height, width, and depth you want.

Is this accurate enough for commissions or selling work?

For most pieces, yes. But if you’re making lids that must fit or work that’s being sold to spec, test your clay’s actual shrinkage or grab it from the manufacturer’s data sheet.

Can I use this calculator for raku or low-fire projects?

Yes but raku shrinkage can vary a lot depending on clay and firing style. If you’re raku-firing, test a few sample tiles first before committing to critical pieces.

🧪 How It Works

How This Calculator Works

You enter the finished size. It adjusts for shrinkage based on your clay type. You get your pre-firing dimensions done. All based on real studio use, not textbook theory.

⚠️ Real Talk on Accuracy

Want Precise Results?

Manufacturer specs or your own studio tests will give you the most accurate shrink rate. This calculator’s here to get you close enough for most projects.