Kiln Firing Schedule Calculator (Ramp Rates, Holds, Total Time & Cooling)
Build a programmed kiln firing from up to four ramp-and-hold segments, see how long each takes, the total time to peak, when the kiln will be cool enough to unload, and the checks for a safe bisque or glaze schedule.
How it works
ramp time = ΔT ÷ rate; segment time = ramp + hold · natural cooling T(t) = T_amb + (T_peak − T_amb) × e^(−t/τ), τ ≈ 2 h (test kiln) … 9 h (large); time to temperature = τ × ln[(T_peak − T_amb)/(T − T_amb)]
Programmable kilns run a list of segments, each a rate (°C per hour) to a target temperature plus an optional hold. The physics you are steering around: steam leaves greenware up to ~120 °C, organics and carbonates burn out between 300 and 800 °C (needs oxygen and time), quartz in the clay expands and contracts sharply at 573 °C (fast changes crack pots), and the last hundred degrees plus any hold decide how much the cone falls and the glaze matures. Cooling is out of your hands unless you program a down-ramp, and it takes longer than most people expect — small kilns cool fast enough to shock pots, large kilns take a day. This calculator adds the segments up and estimates the cooling so you know when to be back.
Worked example
A cone 6 glaze schedule in a studio kiln: 60 °C/h to 100 °C with a 30-minute hold (1.25 h + 0.5 h), 100 °C/h to 600 °C (5 h), 150 °C/h to 1,100 °C (3.3 h), then 60 °C/h to 1,222 °C with a 15-minute hold (2.0 h + 0.25 h) — about 12.4 hours to peak. Natural cooling passes 573 °C after roughly 3.1 hours (about 140 °C/h there), reaches 200 °C after about 7.6 hours and 50 °C after about 15 hours, so the kiln can be unloaded around 27 hours after the start.
Frequently asked questions
Why hold at 100 °C when bisque firing?
Greenware that feels dry still holds several percent of water. Above 100 °C that water turns to steam faster than it can leave thick walls and blows the piece apart. A slow candle to 100 °C with a hold (30 minutes to several hours for thick or damp work) lets it leave gently.
Should I program a controlled cool-down?
For glaze firings a slow cool from about 800 to 500 °C (50–100 °C/h) develops matte, crystalline and iron-saturate glazes and reduces crazing in some bodies; it adds 3–6 hours. Small kilns cool so fast naturally that a down-ramp is often worth it; large kilns already cool slowly.
What final ramp rate should I use?
Most controller presets finish at 60–110 °C/h. The Orton cone chart is built around 60 and 150 °C/h; whatever you choose, keep it the same every time so your cones and glazes behave consistently.
Related calculators
Studio ceramics figures are approximate: clay bodies, glaze materials, kilns and studio conditions vary. Test-fire small batches, use witness cones, and follow your kiln manufacturer's electrical and safety instructions.