Reference · Updated August 2026

Kiln cone temperature chart

Every Orton pyrometric cone from 022 to 14, in Fahrenheit and Celsius, at all three published heating rates. Because a cone measures heat work rather than temperature, the rate you fire at changes the answer, and that column is the one most charts leave out.

By the Austin Gallery editors · Updated August 2026

Cone 6 is 2232°F (1222°C), cone 04 is 1945°F (1063°C), and cone 10 is 2345°F (1285°C) using Orton self-supporting cones heated at 108°F (60°C) per hour. Fire the same cone 6 more slowly, at 27°F per hour, and it bends at 2165°F. Fire it fast, at 270°F per hour, and it holds out to 2269°F. That 104°F spread within a single cone number is not measurement noise. It is the entire point of a cone: a cone measures heat work, the combined effect of time and temperature, so a slower firing reaches the same result at a lower peak. Every number below comes from the Edward Orton Jr. Ceramic Foundation, which manufactures the cones and publishes the equivalents.

The full Orton cone chart (self-supporting cones)

This is the table to bookmark. These are Orton's regular self-supporting cones, the series most studio potters buy, shown at all three heating rates in both scales. The heating rate is measured over the last 180°F (100°C) of the firing, not the whole cycle. Blank cells are blank on Orton's own chart, which publishes no slow-rate value for cones 022 through 020.

Orton self-supporting regular (SSB) cones, cone numbers 022 to 14. Source: The Edward Orton Jr. Ceramic Foundation, “Using Orton Pyrometric Cones, Cone Numbers 022-14” (©2016 Orton Ceramic Foundation). Heating rate is the rate during the last 180°F / 100°C of firing. Values are for a mounted height of 1¾ inches above the base, which self-supporting cones have built in. Orton publishes a separate iron-free (SSK) series for reduction firings between cones 010 and 3, with slightly different values.

Why one cone has three temperatures

A pyrometric cone is a carefully formulated ceramic that softens and bends when it has absorbed a specific amount of heat. Orton describes the mechanism as pyroplastic deformation: glass forms inside the cone, gravity pulls the tip over, and the final bending position indicates how much heat was absorbed.

Absorbing heat takes time. A kiln climbing slowly gives the cone longer at every temperature on the way up, so the cone accumulates enough heat work and bends sooner in temperature terms. A kiln racing to the top gives it less time, so the cone needs a higher peak to reach the same state. Orton puts it directly: the temperature required to cause a cone to bend is higher for faster heating rates and lower for slower rates.

The practical consequence is that “cone 6” is not a temperature at all, it is a target condition. Two potters can both fire honest cone 6, one peaking at 2165°F and one at 2269°F, and both are right. It also explains a frustration every new potter hits: a glaze that runs in one kiln and stays dry in another at the identical set point. The set points matched; the heat work did not.

Cones vs a pyrometer: heat work vs temperature

A thermocouple and pyrometer answer “how hot is it right now.” A cone answers “did the work get what it needed.” Those are different questions, and clay and glaze only care about the second one. Orton is explicit that cones do not measure temperature alone but measure heat work, the combined effect of time and temperature, and that electronic controllers cannot measure heat work.

This is not an argument against pyrometers. You need one, or a controller that has one, to run a schedule at all: to ramp at a known rate, to hold, to control cooling. The point is that a thermocouple ages and drifts, it reads one spot in a chamber that is never perfectly even top to bottom, and nothing on the display tells you it has gone soft by half a cone. A digital pyrometer runs the firing; a cone on the shelf next to the pots grades it. Serious studios use both, every load, and that is also how we approached the controller question in our guide to the best kilns for pottery and glass.

What we would keep on the shelf

The cones and hardware that make the chart above usable. Affiliate links, so we may earn a commission at no cost to you.

Orton Self-Supporting Cone 04 (Pkg/25)The bisque witness cone. Self-supporting means the 1¾ in height and 8 degree angle are built in, so the chart values apply as printed.View on Amazon →Orton Self-Supporting Cone 05 (25 Pack)The low-fire glaze cone, and the one AMACO and most commercial raku glazes are formulated to.View on Amazon →Orton Self-Supporting Cone 6 (Pkg/25)The mid-range workhorse. If you fire one cone in an electric studio kiln, it is this one.View on Amazon →Orton BRB Pyrometric Bar Cones, 06Bar cones are the Kiln-Sitter shutoff format. They are not witness cones: keep a self-supporting cone on the shelf too.View on Amazon →Thermomart Digital Kiln Pyrometer (°F / °C)A pyrometer reads temperature, which is the number cones do not give you. Use both: the pyrometer runs the schedule, the cone grades the result.View on Amazon →AMACO Assorted Pointed Stilts, 30-Count KitGlazed ware fired to a vitrified cone will fuse to the shelf. Stilts and a clean shelf are the other half of a successful firing.View on Amazon →

Self-supporting, large, and small cones

Orton sells the same cone formulations in different physical formats, and the format changes the numbers, because a cone bends according to how much of it stands above the base and at what angle.

• Self-supporting cones have a built-in base and stand on any flat surface. Orton states they are the correct height, 1¾ inches exposed above the base, with the 8 degree bending angle built in, and that glaze and kiln manufacturers recommend them. They are the ones to buy: they design mounting error out.
• Large cones are read at 2 inches of exposed height in a plaque set at 8 degrees. Orton notes that if you mount large cones at 1¾ inches instead, you should read them against the self-supporting temperatures.
• Small cones (also called junior or bar cones) are the Kiln-Sitter format, exposed 15/16 inch in a holder. Orton publishes only one column for them, determined at 540°F (300°C) per hour in a gas fired kiln, which is why small-cone numbers look so much higher than self-supporting numbers for the same cone.

One honest caveat on small cones. Orton's printed chart says small cones typically deform 7 to 10°C earlier than a self-supporting cone, so you can subtract 7 to 10°C (12 to 18°F) from a self-supporting value to estimate the small-cone equivalent. Orton's small cones product page says the opposite direction: that small cones used on the kiln shelf deform at about 9°F after large or self-supporting cones of the same number. We are not going to average two of Orton's own statements into a made-up third. Either way the offset is under 20°F, and the practical rule holds: use bar cones to shut the Kiln-Sitter off, and put a self-supporting witness cone on the shelf to find out what really happened.

Small cone temperatures (Kiln-Sitter cones)

Orton small regular cones, for a mounted height of 15/16 inch. Orton determined these values at a heating rate of 300°C/hr (540°F/hr) in a gas fired kiln, and publishes no slow or medium column for this format. Source: Orton Ceramic Foundation.

Large cone temperatures

Orton large regular (LRB) cones, mounted height 2 inches. Orton publishes no slow-rate column for large cones. Cones 13 and 14 are omitted here: Orton flags its large-cone values for those two numbers as having different compositions and different temperature equivalents, and the published cone 14 figures are not internally ordered, so we would rather print nothing than print a number we cannot explain. Source: Orton Ceramic Foundation.

Firing ranges, labeled

Range names like “mid-range” are studio and industry convention, not an Orton standard. The cone temperatures below are Orton's; the range boundaries are how clay and glaze manufacturers actually rate their products, so each row names the manufacturer it comes from rather than pretending the label is universal.

Cone temperatures from Orton. Range boundaries attributed to the manufacturers named: AMACO, Standard Clay Company, Laguna Clay, and Bullseye Glass. Glass fusing has no cone equivalent in normal practice: Bullseye writes its firing schedules entirely in degrees, which is why that row gives a temperature window rather than a cone.

The one cone to keep in stock

Studio Staple

Orton Self-Supporting Cone 6 (Pkg/25)

Mid-range cone 6 is the most-fired glaze cone in American electric studios. Self-supporting means the 1¾ in height and 8 degree angle are built in, so the chart above applies exactly as printed.

~$19 at Amazon →

Which cone to use for common jobs

Always fire to the cone your clay and glaze manufacturers specify, not to a generic recommendation. The single most reliable instruction here is Orton's own: when a Kiln-Sitter shuts the kiln off, place the next cone higher in sequence on the shelf and confirm the result with a witness cone inside the kiln.

How to place and read a witness cone

Stand a self-supporting cone on the shelf where the work is, not tucked in a corner, and leave room for it to fall without touching a pot. Give yourself a view of it: a cone you cannot see through the peephole during the last stretch of a firing only tells you the story afterward, which is still useful but less so.

Orton defines the endpoint as the tip bent to a 90 degree angle, or in clock terms the tip at the 5 o'clock position, and notes the interval from the start of deformation to the tip touching the shelf is typically 15 to 25 minutes. A barely leaning cone means the kiln came up short. A cone melted into a puddle means it went well past. The most informative thing you can do in an unfamiliar kiln is set three cones together, one below your target, one at it, and one above: the pattern of which bent and which did not tells you in one firing what a season of guessing will not.

Orton also notes that reducing atmospheres affect the bending behavior of the red iron oxide cones between numbers 010 and 3, where the iron can reduce and the cone can look matte, green, or bloated, and recommends the iron-free series for reduction firings in that band. If you fire gas reduction in that range, buy the iron-free cones and use Orton's SSK columns rather than the table above.

Sources

• The Edward Orton Jr. Ceramic Foundation, “Using Orton Pyrometric Cones, Cone Numbers 022-14” (©2016). Every temperature equivalent on this page, in both scales, for all cone formats and heating rates.
• Orton Ceramic Foundation, Pyrometric Cones. Heat work vs temperature, and the statement that controllers cannot measure heat work.
• Orton, Self-Supporting Cones and Orton, Small Cones. Mounting heights, the 8 degree angle, and the small-cone offset (which differs from the printed chart, as noted above).
• AMACO Low Fire Glazes. Bisque to cone 04 (1063°C / 1945°F), glaze fire to cone 05, and the cone 05 raku glaze specification.
• Standard Clay Company and Laguna Clay. Published firing ranges for named earthenware, stoneware, and porcelain bodies.
• Bullseye Glass, Writing Firing Schedules for Fusing and Slumping. Confirms glass firing is scheduled in degrees rather than cones.

Questions

Keep reading

• Clay shrinkage and absorption rates: the companion reference, including how to measure your own clay and what absorption says about whether a body actually matured at the cone you fired it to.
• The best kilns for pottery, glass and ceramics: which kilns reach which cones, and why programmable control is the feature that matters.
• The best pottery wheels: the other half of a working studio.
• Gifts ceramicists actually use: a cone pack is genuinely one of them.
• Pottery classes in Austin: fire in someone else's kiln first if you can.

All cone temperature equivalents are published by The Edward Orton Jr. Ceramic Foundation (©2016 Orton Ceramic Foundation) and are reproduced here with the heating rate and cone format stated for each value. Orton notes these tables are a guide for cone selection and that actual bending temperature depends on firing conditions; cones measure heat work rather than temperature, so a chart value is a starting point and every potter should verify with witness cones in their own kiln. Compiled by the Austin Gallery editors, August 2026. Austin Gallery may earn a commission from product links on this page at no cost to you.