A shrinkage ruler made for your clay.

A hand holding an inch clay shrinkage ruler across a freshly thrown pot on a pottery wheel

Work out how big to make your piece before it shrinks in the kiln.

Choose your ruler See how it works

9.45-inch ruler
Choose your shrinkage percentage: 10–18%

How it works

Measure your wet clay

Then follow the ruler’s arrows to see its fired size.

Start with the size you want

Then follow the ruler’s arrows backwards to see how big to make your wet clay.

A shrinkage ruler between a wet pot on the wheel and its smaller fired size above

The ruler

Dimensions

9.45 inches long × 0.98 inches wide × 0.08 inches thick.

Made for your clay

Each ruler has its own shrinkage percentage. Choose from 10–18%, in centimetres or inches. Available individually or as a set.

Made from durable PLA plastic

With a little flex (if you’re into twanging rulers).

Which shrinkage
percentage do I need?

Find your clay’s shrinkage rate.

Read our measuring guide

Start with your clay supplier Look for the shrinkage percentage on your clay’s product page or technical data sheet. Check that it covers wet-to-fired shrinkage at your firing temperature.

Test your clay's shrinkage Measure a test piece while wet, then again after it comes out the kiln.

Not sure which shrinkage percentage to choose? We also sell sets with a range of shrinkage percentages, whether you’re buying for yourself or as a gift.

Shop ruler sets

Questions about the ruler?

How do I choose my shrinkage percentage?

Start with your clay supplier’s linear shrinkage figure, or measure a test piece through your own drying and firing process. Linear shrinkage means the change in length, not volume. Match the shrinkage rate to the stages you are measuring between. Read our measuring guide.

Can I choose a custom percentage?

Choose a whole-number percentage from 10% to 18%. Need a custom percentage? Contact us.

Will my finished piece fit exactly?

The kiln gods don’t offer guarantees, and neither can our ruler. Clay, moisture, forming, drying and firing affect the result. Test critical dimensions and allow suitable clearance. A lid and pot made from the same clay and fired together often shrink together.

Do you deliver to my country?

We deliver to United Kingdom, Algeria, Angola, Argentina, Australia, Austria, Bahrain, Bangladesh, Belarus, Belgium, Brazil, Bulgaria, Cambodia, Cameroon, Canada, Chile, Colombia, Costa Rica, Côte d’Ivoire, Croatia, Cyprus, Czechia, Denmark, Dominican Republic, Ecuador, Egypt, El Salvador, Estonia, Ethiopia, Finland, France, Georgia, Germany, Ghana, Greece, Guatemala, Hong Kong, Hungary, Iceland, India, Indonesia, Ireland, Israel, Italy, Japan, Jordan, Kazakhstan, Kenya, Kuwait, Latvia, Liechtenstein, Lithuania, Luxembourg, Madagascar, Malaysia, Malta, Mauritius, Mexico, Morocco, Mozambique, Myanmar (Burma), Nepal, Netherlands, New Zealand, Nicaragua, Nigeria, Norway, Oman, Pakistan, Panama, Paraguay, Peru, Philippines, Poland, Portugal, Puerto Rico, Romania, Saudi Arabia, Senegal, Singapore, Slovakia, Slovenia, South Africa, South Korea, Spain, Sri Lanka, Sweden, Switzerland, Taiwan, Tanzania, Thailand, Tunisia, Türkiye, Uganda, United Arab Emirates, United States, Uruguay, Uzbekistan, Vietnam, Zambia and Zimbabwe. Select your country at checkout to see the delivery cost.

When will my ruler arrive?

We ship our rulers from the UK with Royal Mail.
We dispatch orders the same or next day.
Estimated arrival is 2-3 days in the UK and 4-7 days internationally.
Customs clearance and local disruption can delay delivery.

PoodlePotter

Something I made
for potters like me.

👋 I’m Zoë, The Poodle Potter. I started making these rulers because I didn’t want to work out shrinkage percentages with clay on my hands (and sometimes in my hair...!).