How long to preheat an Ooni, and how to know the stone is ready

Ooni gives a number for each oven. The Koda 12 reaches its top temperature of 950°F (500°C) in as little as 15 minutes. The Koda 16 can reach 950°F in 20 minutes. The Karu 12 reaches what Ooni calls the ideal baking temperature of 850°F (450°C) in as little as 15 minutes, with a 950°F maximum.

Those are fair-weather figures for the oven at full output. The number that matters is the stone. Ooni's first-pizza guide says preheating can take up to 20 minutes depending on the oven, that you check the stone with an infrared thermometer, and that you are ready to cook when it reads 750°F. In cold weather Ooni's rough guide stretches to at least 15 minutes and at most 25 to 30, and it says the thermometer is the only way to be sure.

So the practical answer is: light it, wait the time Ooni lists for the model, then read the middle of the stone. Launch at 750°F or above, and not before.

Ooni's preheat figures by model

The figures below come from Ooni's product pages and its specification comparison tables.

The 12-inch ovens are quicker because there is less steel and stone to heat. The Koda 16 carries a larger cordierite stone and an L-shaped burner, and takes the extra five minutes for it. On the Karu 12, Ooni says to keep the chimney vent closed for low heat and smoky flavour and open to reach the oven's maximum temperature, so a preheat toward pizza temperatures is done with the vent open. A Karu run on wood also depends on how well the fire is fed, which is why Ooni's cold-weather range says preheat "can vary depending on the fuel type." The Koda 12 and Koda 16 comparison covers what else the extra size changes.

What temperature the stone should be

Ooni's targets are narrower than the 950°F headline. You are ready to cook at 750°F. Ooni calls 750 to 850°F ideal for Neapolitan-style pizza and says hotter is not always better. At those temperatures the pizza cooks in 60 to 90 seconds and wants a turn every 20 to 30 seconds for an even bake. Ooni's getting-started guide gives the same shape: a Neapolitan-style pizza ready in under 2 minutes, turned every 20 to 30 seconds with the peel or a turning peel, and a stone back at 715 to 850°F (380 to 450°C) before a second pizza launches.

The upper limit is real too. In hot weather Ooni says to keep an eye on the temperature so it does not exceed 932°F (500°C). A stone at the top of the range chars the base before the top is done, which is the usual reason a first pizza comes out black underneath and pale on top. If that is happening, turn the flame down and let the stone settle toward 750°F rather than launching faster.

The launch is its own skill and a cool stone makes it worse, because a base that does not set on contact is a base that folds. That side of the problem is covered in pizza stuck to the peel.

How to read the stone with an infrared thermometer

Ooni says the infrared thermometer is the only way to be sure the stone has reached temperature. The Karu 12 has no built-in thermometer. Ooni's FAQ for it says so directly and points owners to its infrared gun.

Three details on Ooni's own thermometer explain how to get a trustworthy number from any infrared gun.

Emissivity. Ooni's thermometer comes preset for the cordierite stones in its ovens, with an adjustable emissivity setting for steel and cast iron. A general-purpose gun left on its default may read a ceramic stone differently, so check its manual for a setting close to what it uses for ceramics before trusting a reading to within a few degrees.

Spot size. Ooni lists a 10:1 distance-to-spot ratio. At 10 inches from the stone that is a 1-inch circle. At arm's length from the oven mouth it is closer to 3 inches. Aim at the centre where the pizza will land, not the back edge by the flame, and take the reading from the same distance each time.

Scan, do not snapshot. Ooni's model has a scan mode that records minimum, maximum and average across an area during heat-up and recharge, and it is designed for exactly those two moments. Sweep across the stone from front to back. If the front reads 650°F and the back reads 850°F, the oven needs another few minutes with the flame lower, not a pizza.

Recovering the stone between pizzas

The stone loses heat to every pizza it cooks, and the second launch is where most undercooked bases happen. Ooni describes the stone as a rechargeable battery: cooking back to back drains it, launching onto a stone that is not as hot as it should be gives a less crispy crust or an undercooked base, and waiting a few minutes lets it heat back up. It also says an oven that has been running for hours will be hotter than one that just started, and a spot that was just cooked on will be cooler than an unoccupied spot, so check the temperature often.

Two habits follow from that. Read the stone before every launch, not just the first, and wait for 715 to 850°F. And do not land every pizza in the same place. Ooni says shifting each launch slightly left, right, forward or back keeps the stone at the desired temperature, and that this is easier in a 16-inch oven than a 12-inch one. Ooni's specification tables put the Koda 12 and Koda 16 recharge at 3 minutes 30 seconds and the Karu 12 at 2 minutes. Treat that as the fair-weather gap between pizzas and let the thermometer confirm it. The Koda 16 review covers how the larger stone changes a run of pizzas.

How cold and wind change the preheat

Cold air pulls heat out of the oven body and stone the whole time it is running, so the same flame takes longer to get the stone to 750°F and longer to bring it back after each pizza. Ooni's guidance for winter cooking is at least 15 minutes and at most 25 to 30, varying by fuel, and it says the recharge between bakes takes a little extra time in colder weather. Light rain, cold temperatures and snow do not stop the oven working, in Ooni's words, though it does not recommend cooking in severe weather.

Wind is the bigger variable because it can put the flame out. Ooni says to position the oven so the wind hits the back of it, which pulls the flame forward to the oven mouth instead of pushing it back into the oven or extinguishing it. That applies to gas and to wood or charcoal, and Ooni adds a caution about very high winds. The Koda 16 has a flame safety device that cuts the gas if the flame blows out. If the flame keeps going out on a gusty day, the fix is the oven's position, and Ooni's manual covers relighting.

The cheapest cold-weather shortcut is where the stone lives between cooks. Ooni's biggest time-saving tip is to store the stone indoors at home once it has fully cooled, so it starts dry and warm. A stone that has sat in a damp oven all week is carrying water that has to boil off before it can climb, and Ooni's stone-care guidance is blunt that a soaked stone may break the next time it heats up. Dry stone, back to the wind, thermometer at 750°F. The clock on the product page is the least important of the three.