A fan oven (a convection oven in the US) blows hot air around the oven. A sourdough loaf needs a moist surface for its first minutes in the oven, and the moving air works against that. The short version: bake the loaf covered, on the plain Bake setting with the fan off, if your oven allows it. If it does not, lower the temperature as the oven's manual says, keep the cover on, and judge the loaf by its internal temperature rather than the clock. The bake times on this site and in the Loaf & Levain recipes are for the regular Bake setting, not Convection Bake or Convection Roast.
What the fan does to a loaf
Three things, all in the direction of a drier, darker, earlier-setting crust:
- It dries the surface. Moving air carries moisture away from the dough faster than still air. Early in the bake the surface needs to stay soft and stretchy so the loaf can expand and the score can open; a surface that dries early sets into a shell sooner.
- It browns faster. Moving air transfers heat to the crust more quickly, so the crust can look done while the center is not.
- It clears steam from an open tray. On a stone or steel with a tray of boiling water below, the fan spreads that steam around the oven and toward the vent, so expect it to thin out sooner than on Bake.
A fan is not the only reason a loaf comes out flat or pale. If a loaf had little oven spring, check the other causes too: the troubleshooting guide covers proofing, shaping and preheating.
Bake covered, with the fan off
The simplest fix is to take the fan out of the picture:
- Cover the loaf for the first 20 minutes. A preheated Dutch oven or a cover traps the loaf's own steam right against its surface, so the air outside the cover matters much less in that phase. Dutch oven vs. baking stone compares the pot with a stone, and sourdough without a Dutch oven shows how to cover a loaf with an inverted stainless-steel bowl or a deep roasting pan on a stone, steel or heavy baking sheet. Its safety notes cover what not to put in a hot oven (no glass), handling a hot cover with oven mitts, and keeping your face clear of the steam.
- Use the Bake setting with the fan off. With the fan off, the uncovered phase browns at the pace the recipe's times assume.
- Keep the recipe's clock as a guide, not a rule. In the Loaf & Levain recipes that is 60 minutes of preheat at 250°C (480°F), 20 minutes covered at 250°C (480°F), then about 25 minutes uncovered at 230°C (445°F), until the crust is deep brown and the center has reached the temperature below.
With a steam tray instead of a cover, the fan matters more, because nothing holds the steam against the loaf. In a fan-only oven, that is a reason to switch to a cover.
Finding the fan-off setting
Oven symbols vary by maker, so the symbol table in the oven's manual is the reliable answer. Lost the manual? Look for it on the maker's website under the model number on the plate inside the door or on the frame.
- On US ovens, look for Bake for the fan-off setting, and Convection Bake, Convection Roast or similar for the fan settings.
- On UK and European ovens, two lines, one along the top and one along the bottom of a square, can mean top and bottom heat without the fan (sometimes called conventional). A fan symbol inside a circle means the fan is on with heat; a fan symbol alone can also be a defrost setting with no heat, so check the manual.
- Some settings combine both, for example a fan with a bottom line. Those still blow air over the loaf.
Some ovens also run a cooling fan on every setting, which blows air out of the case rather than through the oven. If you hear a fan on Bake, the manual says which kind it is.
If your oven only bakes with the fan
Some compact and combination ovens have no fan-off setting. You can still bake good sourdough in them, with three changes:
Lower the temperature as the manual says. Some manuals say how much lower to set a fan setting. Some ovens lower it automatically on a convection setting; the manual says whether yours does, so you do not lower it twice. If the manual gives no figure, the common convention in UK and European recipes is about 20°C lower: recipes there may print both, such as "220°C, fan 200°C". That is a recipe-writing convention, not a measured rule for your oven. By that convention, the recipe clock above becomes about 230°C (445°F) covered and about 210°C (410°F) uncovered. Preheat at the lowered temperature for the covered phase (about 230°C (445°F) by that convention), for the full 60 minutes. An inexpensive oven thermometer on the rack shows what the oven actually reaches, which matters more than the dial.
Keep the cover on, and on a few minutes longer if needed. The cover is the one thing that shields the surface from the fan during the phase when steam matters most. If the crust colors fast once the cover is off, or the score barely opens, a practical step is to keep the cover on about 5 minutes longer next time. That is a starting point from practice, not a tested figure, so note what you changed and compare the loaves.
Go by the doneness signs, not the clock. In a fan oven the crust can brown ahead of the timer, and a dark crust does not prove the center is baked. If the crust is as dark as you want but the center is not yet hot enough, lay a loose sheet of foil over the top for the rest of the bake, a common way in practice to slow browning, and keep baking to the internal temperature below.
There is no general figure for how much less a loaf springs with the fan on. Ovens differ too much in fan speed, venting and how close the fan sits to the loaf.
How to tell the loaf is done
Use the same signs whatever the setting:
- Internal temperature: at least 96°C (205°F) in the center; 96–99°C (205–210°F) is the common practice for a lean sourdough loaf, as in why sourdough is gummy, which also says what to do when the reading is low. Push an instant-read thermometer through the bottom into the middle.
- Crust: deep brown all over, including the bottom.
- Sound: a hollow sound when you tap the bottom is a useful extra sign, but on its own it can mislead. The thermometer decides.
Then cool the loaf on a rack for at least 1 hour before slicing; a fully baked loaf cut while warm can still seem gummy.
Preheating with the fan
A fan heats the oven air quickly, so the display can reach the set temperature well before the pot, stone or steel has heated through. Their stored heat drives the loaf's spring, so give them the full 60 minutes whatever the display says.
Frequently asked questions
Does a convection oven ruin sourdough?
No, but it changes the bake: a drier surface, faster browning and less steam from an open tray. Bake covered with the fan off, or, with the fan on, lower the temperature, keep the cover on and bake to the internal temperature.
Can I bake sourdough in a Dutch oven with the fan on?
Yes. During the covered phase the lid holds the steam, so the fan has less effect. Once the lid comes off, the crust will brown faster than on Bake, so start checking the color and the internal temperature earlier.
How much lower should I set a fan oven for bread?
Follow the oven's manual first. If it gives no figure, the common UK and European recipe convention is about 20°C lower. Treat that as a starting point and check the loaf's internal temperature.
Is a steam tray worth it in a fan-only oven?
It helps less, because the fan spreads the steam around the oven and pushes it toward the vent. A cover over the loaf keeps the steam where it is needed; sourdough without a Dutch oven gives the steps.
Plan the bake
The oven is the last step. Put your flour, starter and kitchen temperature into the bake schedule calculator to plan the schedule from levain to bake, so the loaf reaches the oven ready.