Firing

Pottery Cone Chart & Temperature Calculator

Convert Orton cone numbers to equivalent temperatures in Celsius and Fahrenheit. Free pottery cone chart with firing speed correction.

Reviewed by ClayCalc Editorial · Updated

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Enter your measurements above and click Calculate.

Orton Cone System

Pyrometric cones are small pyramids made from ceramic materials calibrated to bend at specific heat-work levels. They measure the combined effect of temperature and time, not just peak temperature — making them more accurate than thermocouples alone for determining glaze and clay maturity.

The Orton cone system ranges from cone 022 (the lowest, ~586°C) to cone 13 (the highest, ~1348°C). Note the counterintuitive numbering: "0" numbers go from 022 (coolest) down to 01, then the positive numbers start at 1 and go higher.

Firing Speed Effect

This calculator applies a ±20°C correction for firing speed relative to the standard test speed of 60°C/hr. Fast firing produces less heat work at a given temperature — the equivalent of firing approximately one cone cooler. Slow firing produces more heat work — equivalent to firing one cone hotter.

Low-Fire

Below Cone 1
< 1154°C

Mid-Fire

Cone 2–6
1162–1222°C

High-Fire

Cone 8–13
1263–1348°C

Method & review note

About this calculation

Produces a planning estimate from the values entered. Nameplate power, utility billing, kiln condition, load and witness cones remain the authoritative studio checks.

Reference: Orton Ceramic — Pyrometric Cone Resources. See the editorial methodology for testing, precision and corrections.

Input handling: Values are sent to the ClayCalc server for this request and are not written to the application database.

Read the Kiln Firing Cost

Frequently Asked Questions

Why is cone temperature different from thermocouple temperature? expand_more
Cones measure heat work — the combined effect of temperature AND time. A thermocouple measures instantaneous temperature. Two identical thermocouples can show the same peak temperature but cones can bend differently if one firing was faster than the other.
What is the difference between low-fire, mid-fire, and high-fire? expand_more
Low-fire is below Cone 1 (below ~1154°C). Mid-fire is Cone 2–6 (~1162–1222°C). High-fire is Cone 8–13 (~1263–1348°C). Most commercial clays and glazes are rated for a specific range.
Are Orton and Seger cones the same? expand_more
No. Orton (US) and Seger (European) cone systems use different numbering and have slightly different melting points. Always verify which system your clay or glaze manufacturer uses.