Kiln Firing Schedule Calculator

In short A firing schedule is a list of ramps and holds, and working out how long it takes is division: each segment is its temperature rise divided by its rate, plus any hold. Trivial arithmetic, and still worth doing, because four sensible-looking lines routinely add up to a firing that finishes at three in the morning. Twenty degrees to 600 at 100°C an hour, then to 1,100 at 150, then a slow final ramp to 1,222 at 60 with a fifteen-minute hold, comes to eleven hours and twenty-five minutes before the kiln has even started cooling. THE LAST RAMP IS THE ONE THAT DECIDES YOUR RESULT. Because a cone measures heat work rather than temperature, the speed of the final climb determines which cone actually bends. A slow finish — 60°C an hour or less — gives the glaze time to melt and the cone time to move, which is why the same peak temperature reached two different ways gives two different pots. If you change one thing in a schedule, change that. HOLDS ARE NOT FREE EITHER. A hold keeps adding heat work at the temperature where it counts most, so twenty minutes at the top can be worth the better part of a cone. That is a useful tool when you want it and an expensive accident when you do not, and it is the usual explanation for a kiln that "reached the right temperature" and still over-fired. Two things this page deliberately does not count. Cooling, which is where crystals grow, where glaze surfaces develop and where most cracks happen — a controlled slow cool through the first couple of hundred degrees below peak changes a glaze more than most recipe tweaks do, and opening the lid below about 250°C is the commonest way to crack a shelf. And element wear, which is real: every hour spent above 1,100°C for no reason is quietly buying you a new set sooner.