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Clay & Pottery Calculators
Shrinkage. Firing costs. How far a bag of clay really goes. Pick your clay, pick your level, and let this page do the arithmetic while your hands stay muddy. No fluff, no digging through other pages. Just the numbers.
Set it once
First, two quick taps.
Which level are you, and which clay is on your wheel? Every calculator below updates the second you answer, and keeps updating as you play.
Quick heads up: almost everything on this page is a member perk. The clay, the free bisque firings, the 10,000 square feet around them. The prices you’re seeing are full price. Fixing that takes about two minutes.
Become a memberCalculator no. 1
The shrinkage calculator
Clay shrinks as it dries, then shrinks again in the glaze fire. B-Mix gives up about 12% from wet to done. Here’s what that means for the piece in front of you.
Throw it at 10″ today and it comes out of the glaze kiln at about 8.8″.
Three sizes people actually chase:
Berlin Gray’s maker lists drying shrinkage (5.7%) and firing shrinkage (6.7% at 1300°C) separately. We combined them to about 12%. Their test firing runs hotter than ours, so treat that number as the high end.
Shrinkage numbers are the manufacturers’ averages. Clay is a natural material and every batch has a personality, so give yourself a little grace in either direction.
Calculator no. 2
The firing cost calculator
Glaze firings cost five cents per cubic inch of the box your piece fits inside. Wide, times long, times tall. Bisque firings are free. That’s the entire pricing model, and here it is with sliders.
Under 100 cubic inches, so the flat $4.80 minimum applies. Told you it was friendly.
Okay, that one is beyond everyday math. Firing charges cap at $600, and the kiln itself tops out around 22″ wide by 44″ long by about 52″ tall. Building something enormous? Wonderful. Come talk to us at the studio first and we’ll figure it out together.
Anything 100 cubic inches or under fires for a flat $4.80. A mug, basically.
Small pieces that fit on one 6″ cookie, with a quarter inch between them, count as one piece when they total under 100 cubic inches. One cookie, one $4.80.
Bisque firings cost members nothing. Zero. We only charge for glaze firings.
Charges cap at $600, and truly giant pieces deserve a real conversation. Come find us before you build the monument.
The firing page charges in set increments, so your exact total may round a hair from the estimate above.
Calculator no. 3
The bag math calculator
A 25 lb bag of B-Mix runs $36 at your level. Here’s how far it actually stretches once you start pulling walls.
At 1.25 lb each, that’s about $1.80 of clay in every piece you make.
Throwing weights are ballparks. Your mug is not our mug, and that’s kind of the point. The math also assumes every ounce ends up on the wheel, which is adorable of it.
The full lineup
Every clay we stock, one table.
Tap any row to load that clay into the calculators above. Prices are per bag, at your level, in the studio.
| clay | cone | shrinks | absorbs | bag | your price |
|---|---|---|---|---|---|
| 52 Buff | 5 | 10% | 3.5% | 25 lb | $28 |
| B-Mix w/Grog | 5 | 11% | 2.75% | 25 lb | $32 |
| B-Mix | 5 | 12% | 2.3% | 25 lb | $36 |
| B-Mix w/Specks | 5/6 | 12.47% | 2.47% | 25 lb | $36.50 |
| Speckled Buff | 5 | 12% | 3% | 25 lb | $40 |
| Half & Half | 5 | 12% | 0.5% | 25 lb | $40 |
| #16 Porcelain | 6 | 13.9% | 0.12% | 25 lb | $44.50 |
| Berlin Gray | 1200 to 1300°C | about 12% | 0.1% | 27 lb | $49 |
We don’t ship clay, and outside clay can’t come through the door. Zero tolerance on that one. Everything on this table lives at the studio, waiting for you.
That’s the whole page
Enough math. Go make the thing.
This page will be right here holding all the numbers, every single time you need it. Bookmark it, use it for a decade. And if you’re not a member yet and somehow read this far: you clearly like knowing exactly what things cost. You are going to love it here.
The fine print, lovingly
Prices were accurate the day we built this page. If the page and a price tag ever disagree, the price tag wins.
Clay and kiln firings are in-studio, members-only purchases. Firing purchases from non-members are non-refundable, so please don’t buy one by accident.
Shrinkage and absorption numbers are manufacturer averages, and clay does what clay wants. Expect small batch-to-batch drift.
Berlin Gray’s shrinkage figure is our combination of the maker’s separate drying (5.7%) and firing (6.7% at 1300°C) numbers.
The firing page charges in set increments, so exact totals can round slightly from the estimates here.