Two different reasons to preheat
Thermal mass. A pizza stone, a cast iron pan and a heavy griddle plate all store heat and give it back to the food. Cold, they take heat from it. This is the case where preheating is not optional and where time matters most.
Air temperature. An oven bakes by the air and the walls around the food. Put a cake into a cold toaster oven and the outside sets before the inside rises. The BLACK+DECKER toaster oven at $59.99 says it plainly: “preheat for 10 minutes to ensure consistent cooking and crisp results”.
Where it barely matters
Anything with a fan and a light metal basket comes up fast. An air fryer reaches temperature in a few minutes, and many recipes skip the preheat entirely; adding two or three minutes to the cook time does the same job.
The pizza stone, which needs the longest
A stone has to come to temperature through its whole thickness, not just at the surface. The Unicook at $33.99 is 0.6 inch thick and about 6.8 pounds; the Pizza Divertimento is the same 15 × 12 × 0.6 inches and publishes the figure the others leave out: at least 30 minutes at about 480 °F.
Thickness decides it. A thin stone comes up fast and gives its heat to the first pizza; a thick one takes longer and holds through the second. An oven light going out after ten minutes only tells you the air is hot.
What to do
Preheat anything with mass, and give it longer than feels reasonable — 30 minutes for a stone, starting cold. Preheat any oven you bake in. For everything else, follow the manual that came with the appliance — it is the only document that knows your specific machine.
Prices quoted in this text were read on 2026-10-17. The live price is at the top of the page.
What readers want to know
Which appliances really need preheating?
Anything with thermal mass, and any oven you bake in. A pizza stone needs the longest: the Pizza Divertimento set publishes at least 30 minutes at about 480 °F, starting from a cold oven — the most concrete instruction on this site. A toaster oven needs less: the BLACK+DECKER publishes 10 minutes. An air fryer, with a fan and a light basket, needs a few minutes at most.
Why do so few makers publish a preheat time?
It varies with the room, the load and the setting. On the pizza stones sold on Amazon.com on this site, the Unicook and the Ritual Life say "preheat the stone" and give no time, and the Emile Henry says nothing at all. Where a maker does publish one, it is worth noting.
Should I put a pizza stone into a hot oven?
No — put it in cold and heat them together. A cold stone set on a hot rack, or a hot stone set on a cold counter, takes a temperature difference across the material, which is what cracks stones. The Pizza Divertimento listing says the same: place the dry stone in a cold oven, then preheat.
Last reviewed 17 October 2026
