Why is my oven temperature wrong?
How to find out what your oven is really doing, and how to work around it without a repair.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 2 min
Short answer
Most domestic ovens run 10-20°C out and have hot and cool spots. Put an oven thermometer on the middle shelf, preheat for twenty minutes, and compare. Then adjust the dial by the difference — you rarely need to fix the oven itself.
The dial sets a target for a thermostat that cycles on and off, so the real temperature swings around the setting rather than holding it. Add door seals, fan behaviour and shelf position, and the number on the dial is best treated as a starting point.
What you'll need
- Oven thermometer
- Baking tray (optional)
Step by step
- Buy an oven thermometer and hang it on the middle shelf.They cost very little and explain a surprising number of baking failures.
- Preheat for a full 20 minutes before reading it.Most ovens announce 'ready' when the air hits temperature, long before the walls and shelves have. That is why the first batch behaves differently.
- Read the difference and adjust the dial by that amount.If it reads 165°C when set to 180°C, set it to 195°C for a 180°C recipe. Simple offset, no repair needed.
- Map the hot spots by baking a tray of scones or bread rolls.Whichever browns first marks the hot area. Rotate trays halfway through baking to even it out.
- Check the door seal.Close the door on a sheet of paper. If it pulls out easily, the seal has perished and heat is escaping. Seals are usually a cheap DIY replacement.
- Account for fan ovens.Fan ovens run roughly 20°C hotter in effect. Most recipes are written for conventional ovens, so reduce by 20°C unless told otherwise.
- Stop opening the door to check.Each opening drops the temperature 20-30°C and it takes several minutes to recover. Use the light and window.
Tips
- Preheat a heavy baking sheet or pizza stone in the oven. It stabilises the temperature and evens out the cycling considerably.
- The top shelf is hotter in most conventional ovens; the bottom is cooler and can scorch bases. Middle is the default for a reason.
- If the oven is out by more than 30°C or wanders unpredictably, the thermostat is likely failing and is worth having looked at.
Common mistakes
- Trusting the preheat beep — It signals air temperature, not a fully heat-soaked oven. Twenty minutes is the realistic figure for baking.
- Assuming recipes account for a fan — Most are written for conventional ovens. Using a fan at the stated temperature effectively bakes 20°C too hot.
- Blaming recipes for repeated failures — A consistently wrong oven produces consistently wrong results across every recipe you try.
Questions people ask
How do I check if my oven temperature is accurate?
Hang an oven thermometer on the middle shelf, preheat for twenty minutes, and compare the reading with the dial. Then offset the dial by the difference.
Should I reduce the temperature for a fan oven?
Yes, by about 20°C from what a conventional recipe states, unless the recipe explicitly gives a fan temperature.