Clay Shrinkage Rates Calculator

Name: CraftCalc
Price range: Free

Comprehensive shrinkage rate database for all clay types and firing temperatures. Calculate exact compensation factors for pottery projects, predict final sizes, and ensure perfect fit for functional ceramics with professional accuracy.

Calculate Shrinkage NowFree • Precise • Professional Data

Understanding Clay Shrinkage

Clay shrinks during drying and firing. Total shrinkage typically ranges from 8-16% depending on clay type and firing temperature.

Drying Shrinkage (Leather Hard)

Initial shrinkage as clay loses moisture content. Typically 2-6% depending on clay body and original moisture level.

• Porcelain: 4-6% drying shrinkage
• Stoneware: 3-5% drying shrinkage
• Earthenware: 2-4% drying shrinkage

Firing Shrinkage (Bisque + Glaze)

Additional shrinkage during bisque and glaze firing. Varies significantly with clay type and firing temperature.

• Cone 04: 4-6% firing shrinkage
• Cone 6: 6-9% firing shrinkage
• Cone 10: 8-12% firing shrinkage

Clay Type Shrinkage Rates

Porcelain

Drying4-6%

Cone 66-8%

Cone 108-12%

Total12-18%

Stoneware

Drying3-5%

Cone 65-7%

Cone 107-10%

Total10-15%

Earthenware

Drying2-4%

Cone 044-6%

Cone 66-9%

Total8-13%

Shrinkage Compensation Formulas

Basic Formula

Wet Size = Final Size ÷ (1 - Total Shrinkage%)

For a 10" final bowl with 12% total shrinkage:

10" ÷ (1 - 0.12) = 10" ÷ 0.88 = 11.36" wet size

Reverse Calculation

Final Size = Wet Size × (1 - Total Shrinkage%)

For a 12" wet piece with 12% total shrinkage:

12" × (1 - 0.12) = 12" × 0.88 = 10.56" final size

Factors Affecting Shrinkage

Clay Body Plasticity

Higher plasticity clays shrink more during drying

Firing Temperature

Higher firing temps cause greater vitrification shrinkage

Grog Content

Added grog reduces overall shrinkage rates

Wall Thickness

Thicker sections may experience uneven shrinkage

Testing Your Clay Body

Why Test Your Clay?

Different clay suppliers, recipes, and even clay batches can have varying shrinkage rates. Testing ensures accuracy for important functional pieces like lids, handles, and fitted forms.

Simple Test Bars

1. Roll clay into 10cm x 2cm x 1cm bars
2. Mark exact measurements when wet
3. Measure at leather hard stage
4. Measure after bisque firing
5. Measure after glaze firing

Measuring Technique

• Use digital calipers for accuracy
• Measure in same spot each time
• Test multiple bars for average
• Record temperature and clay batch
• Keep detailed shrinkage log

Recording Results

• Wet to leather hard %
• Leather hard to bisque %
• Bisque to glaze fired %
• Total wet to fired %
• Create shrinkage chart

Calculate Your Clay Shrinkage

Get precise shrinkage calculations for perfect pottery sizing

Start Shrinkage Calculator