An oven does not hold one temperature. It cycles: the element heats until the sensor says the setpoint has been reached, switches off, the air cools, and it heats again. The dial number is the middle of a swing rather than a steady state, and a lot of "my oven is wrong" is actually "my oven swings more than I expected."
The way to find out which you have is a thermometer and an hour, and after that most ovens have an adjustment the manufacturer put there for exactly this and most owners have never opened the manual page that describes it.
The test
You need a standalone oven thermometer. Not the built-in display, which is reading the sensor you are trying to check.
- Put the thermometer in the middle of the oven, on the rack you normally bake on, not touching the walls.
- Set the oven to a temperature you actually use for baking.
- Wait for it to preheat, and then wait longer. The preheat signal tells you the sensor has reached the setpoint once. It does not mean the whole cavity and the racks and the walls are there. Give it another 20 minutes.
- Read the thermometer without opening the door if you can see it through the glass.
- Read it again every 5 minutes for half an hour and write each reading down.
What you now have is the swing and the average, and those are two separate findings.
A swing of some size is normal. That is how a thermostat works.
An average that sits consistently above or below your setpoint is an offset, and that is the fixable one.
Do the test twice on two different days before acting. A single run can be thrown by a door opened once or a thermometer sitting somewhere odd.
The adjustment most people have never used
Many ovens allow the owner to enter a calibration offset, so a reading that is consistently low or high can be corrected without a service call.
Where it is: your manual. The sequence differs by manufacturer and by model, and it is not something to guess at from a general article. Look for "calibration", "temperature adjustment" or "offset" in the index.
What it does: shifts the relationship between the number you set and the temperature the oven targets, usually within a limited range.
Two cautions before you use it.
Only adjust for a consistent offset, established over two test runs, not for one reading.
Write down the original value before you change it. If you never noted the starting point, you cannot put it back.
What is not a calibration problem
Four patterns get reported as "the oven is wrong" and are not.
Everything burns on the bottom. That is heat distribution rather than temperature. Rack position, the pan, and whether a heavy dish is blocking airflow all change it. Try a different rack before changing the calibration.
One side cooks faster. Also distribution, and on a fan oven it can point at the fan. Rotating the pan halfway is the ordinary answer, and a consistent, severe difference is worth reporting.
It takes far longer to preheat than it used to. That is an element or a sensor question rather than an offset one, and it is an observation to collect.
Baking results changed but roasting is fine. Baking is far more sensitive to a small offset than roasting is, which means a change in baking results alone is genuinely consistent with a small calibration drift.
The things that change the answer and have nothing to do with the oven
Where the thermometer sits. Against a wall, on the floor of the oven, or up against a hot rack gives you a reading about that spot rather than about the cavity.
Opening the door. Every opening drops the temperature substantially, and the recovery takes minutes.
What is in the oven. A cold, dense dish pulls the temperature down and it takes time to come back. That is not the oven failing.
Preheat length. Most people underestimate it. The signal is the sensor, not the cavity.
Cleaning. A heavily soiled oven can behave differently, and the self-clean cycle in particular is not a neutral event for the appliance. Whether to use it at all, and the specific warning about fumes and pet birds that JennAir's own manual carries, is set out in is oven self-clean safe. Cleaning without it is covered in how to clean an oven without self-clean.
Where this stops being yours
The oven will not reach temperature at all, or the reading is wildly out. That points at a sensor or an element and is a service call.
A visible break, blister or arcing on a heating element. Stop using it and get it looked at.
Anything involving the gas supply on a gas range. No adjustment on this page touches gas, and a gas smell is not a calibration question. That is an evacuate-and-call situation with its own page in this cluster.
Anything requiring the back panel off. After the appliance is disconnected, and on most units it is a technician's job regardless.
A door that no longer seals or closes fully. Heat escaping past a failed door seal produces exactly the symptom this page is about, and it is worth checking before you conclude anything about calibration. A door gasket is a part on many models but the fitting is model-specific.
If it turns out to need a repair
The repair-or-replace question is a real one and the rule everybody quotes, that you replace when a repair costs more than half a new appliance, is widely attributed and could not be verified at a primary source. Our triage guide reports that failed trace rather than repeating the rule: is this a DIY fix or a service call.
FAQ
How do I check whether my oven temperature is accurate? Put a standalone oven thermometer in the middle of the oven on the rack you normally use, preheat, then wait another 20 minutes, and read it every five minutes for half an hour, writing each reading down. Repeat on a second day before drawing a conclusion.
Why does the temperature keep moving? Because a thermostat cycles the element on and off around the setpoint. A swing is normal. A consistent average above or below the setpoint is the finding that matters.
Can I recalibrate my oven myself? Many ovens have an owner-accessible calibration offset, and the sequence is in your manual rather than general on the internet. Only use it for a consistent offset established over two runs, and write down the original value first.
Everything burns on the bottom. Is that a calibration problem? Usually not. That is heat distribution, which changes with rack position, pan material and whether airflow is blocked. Try a different rack before adjusting anything.
Why does the preheat signal come on before the oven is really ready? Because it reflects the sensor reaching the setpoint, not the whole cavity, the racks and the walls being at temperature. Waiting another 20 minutes after the signal is the practical fix.
My baking changed but roasting seems fine. Is that possible? Yes. Baking is far more sensitive to a small offset than roasting, so a modest drift shows up there first.
Sources: this page contains no temperature offset figure, no cost, no repair price and no lifespan figure, and cites none. The calibration procedure is explicitly routed to the reader's own manual because the sequence differs by manufacturer and model. The self-clean fume warning and the JennAir manual reference are carried from this site's own self-clean article, which records its sources and dates. The unverifiable status of the widely quoted 50 percent repair-or-replace rule is carried from this site's own appliance triage article.
