Glaze Coverage Calculator
Mix enough glaze without drowning in leftovers. Enter the surface area to cover — or size it from a simple form — set your coats and your own measured coverage rate, and get the glaze volume with a waste allowance.
Measure this for your own glaze — it changes a lot with thickness, specific gravity, and whether you dip, pour, or brush.
Formula & how it works
Total area is area per piece × pieces × coats, and glaze volume is total area ÷ coverage rate, then multiplied by 1 + waste ÷ 100.
The cylinder helper uses π × diameter × height for the wall plus π × (diameter ÷ 2)² for the base, doubling the wall when the inside is glazed too.
Worked example
A mug 3.5 inches across and 4 inches tall has roughly 54 in² of outside surface including the base. Twelve mugs at two coats is about 1,290 in². At 100 in² per ounce that is 12.9 oz of glaze, or about 14 oz once you add a 10% allowance.
Estimating glaze well
Measure your own rate
Coverage is the one number nobody can supply for you. A thin, low specific-gravity glaze brushed on covers vastly more area per ounce than a thick dipping glaze, and two potters using the same recipe can differ by half. Measuring once and noting the figure per glaze makes every future batch predictable.
Dipping needs volume, not just coverage
The coverage figure tells you how much glaze ends up on the work. Dipping additionally requires enough depth in the bucket to submerge the piece, which can be many times that amount. The surplus is not consumed and stays in the bucket for next time, but it does need to exist before you start.
Coats compound
Each extra coat multiplies both the glaze used and the applied thickness, and thickness is where many glaze faults begin — crawling, running, and pinholing all trace back to going too heavy. Test tiles at your intended coat count are the cheapest insurance before committing a kiln load.