# Pyrometric Cone Chart

Source: https://potterynest.com/blog/pyrometric-cone-chart
Published: 2026-09-12
Publisher: Pottery Nest

A pyrometric cone chart converts the cone numbers printed on kiln shelves, glaze buckets, and clay bags into actual firing temperatures, and reading it correctly is what keeps a bisque firing from underfiring or a glaze firing from overfiring the clay body underneath it. This reference lists standard large (self-supporting) cone equivalents from cone 022, the lowest common bisque temperature, up through cone 11, near the top of typical studio stoneware and porcelain firing, in both Fahrenheit and Celsius at the standard 108°F (60°C) per hour heating rate.

## Why cones measure heat-work, not just temperature

A pyrometric cone does not simply melt at a fixed temperature the way a thermometer reads one. It bends when it has absorbed a specific combination of temperature and time, called heat-work, which is why the same kiln firing to the same peak temperature at a faster or slower rate will bend a different cone. This is also why cones are the more reliable measure for ceramics than a digital pyrometer reading alone: two kilns can hit the same peak degree number on a controller and still underfire or overfire the ware if their ramp speeds differ, while a witness cone tells you what the clay and glaze actually experienced.

The numbers below assume the standard large cone heating rate of 108°F (60°C) per hour used in most published Orton and Cone Art charts. A slower ramp, common in electric kilns doing a long soak, effectively fires slightly hotter than the chart number at the same peak temperature, and a fast ramp fires slightly cooler, which is why placing a physical witness cone in the kiln remains more trustworthy than trusting the controller's number alone.

[Orton's official pyrometric cone reference](https://www.ortonceramic.com/pyrometric-cones)

## Cone chart: 022 through 06 (low fire and bisque)

Cone 022: approximately 1112°F / 600°C. The lowest commonly used cone, occasionally used for very low-fire glazes and china paint.

Cone 018: approximately 1323°F / 717°C. Used for some overglaze enamels and china paint firings.

Cone 015: approximately 1450°F / 788°C. Another low-temperature decorating range, above most overglazes but below standard bisque.

Cone 010: approximately 1641°F / 894°C. A low bisque temperature sometimes used for extra-porous bisque intended to take glaze very absorbently.

Cone 08: approximately 1751°F / 955°C. A common low bisque firing temperature for studios that want maximum glaze absorption.

Cone 06: approximately 1828°F / 998°C. The most widely used standard bisque firing temperature in hobby and school ceramics, producing bisqueware hard enough to handle safely while still porous enough to take glaze evenly.

## Cone chart: 05 through 1 (mid-low fire glaze range)

Cone 05: approximately 1888°F / 1031°C. Used for many low-fire glazes and some earthenware clay bodies' final maturity point.

Cone 04: approximately 1945°F / 1063°C. A very common low-fire glaze firing temperature, especially for earthenware and many commercial low-fire glaze lines.

Cone 03: approximately 1987°F / 1086°C. Sits between the common cone 04 and cone 02 low-fire glaze ranges.

Cone 02: approximately 2016°F / 1102°C. Used for some earthenware bodies reaching full maturity and select low-fire glazes wanting slightly more heat-work than cone 04.

Cone 01: approximately 2046°F / 1117°C. An intermediate step rarely targeted directly but useful for reading a witness cone that fell between 02 and 1.

Cone 1: approximately 2079°F / 1137°C. Marks the low end of the mid-range firing territory, occasionally used for specific stoneware clay bodies formulated for a lower maturity point.

## Cone chart: 4 through 11 (mid-fire and high-fire stoneware)

Cone 4: approximately 2167°F / 1186°C. A mid-range firing temperature used by some stoneware bodies and glazes formulated for slightly cooler mid-fire kilns.

Cone 5: approximately 2185°F / 1196°C. Close to cone 6 and sometimes used interchangeably depending on the clay and glaze manufacturer's stated range.

Cone 6: approximately 2232°F / 1222°C. The single most common mid-fire target in studio and school electric kilns, where most commercial stoneware clay bodies and a huge share of commercial glazes are formulated to mature.

Cone 7: approximately 2262°F / 1237°C. Sits above standard cone 6, used by some stoneware bodies and glazes wanting slightly more vitrification.

Cone 8: approximately 2280°F / 1249°C. An intermediate step between cone 6/7 and cone 9/10 firing ranges.

Cone 9: approximately 2300°F / 1260°C. Approaches high-fire territory, used by some stoneware and porcelain formulations.

Cone 10: approximately 2345°F / 1285°C. The classic high-fire stoneware and porcelain target used in gas reduction kilns and many wood-fired kilns, where clay bodies vitrify fully and many glazes develop their characteristic depth.

Cone 11: approximately 2361°F / 1294°C. Near the top of typical studio firing ranges, used by a small number of very high-fire clay bodies and glazes.

## Using witness cones and reading a cone pack correctly

Place witness cones, small unfired cones set at a slight forward lean in a cone pack or plaque, where you can see them through a peephole or where they will sit in a representative spot in the kiln, since temperature varies from shelf to shelf. Many potters place a three-cone pack at both the target cone and one cone above and below it, so a bent target cone with the cone above still standing confirms the firing landed correctly rather than overshooting.

A properly fired cone bends over so its tip touches or nearly touches the base, like a candy cane drooping in heat. A cone still standing straight means the kiln underfired relative to that cone; a cone that has completely melted into a puddle means the kiln significantly overfired past it. Reading the full pack, not just the target cone, tells you both whether you hit the mark and by how much you missed if you did not.