According to a test by Cook’s Illustrated in 2011, different ovens set to the same temperature can vary by as much as 90 degrees.
Yes….90 degrees.
If you are an avid baker or cook (or even just an occasional one), this news should be a bit concerning. Or maybe this news is relief; you now have a valid excuse for why your sweet potato fries always burn! Or at least I do…
When we moved in, one of the first things I did was check the oven’s true temperature. It’s an older oven (edited to add: I don’t mean super old by the way. The oven in our last house was 30 yrs old and I doubt this one is more than 10 yrs, so technically, it’s newer to me) and I was concerned about switching to a new-to-me oven without checking things out first. It’s especially important to me because I post my recipes for all of you and I have to be as accurate as possible.
For some reason, I had a bad feeling about this oven, even though it’s quite nice on the eyes.
I set my oven to 350F and placed my oven thermometer (from Kitchen Stuff Plus) in the center of the oven on the middle rack. This would be the first of several tests I would end up doing.
[But it’s called a “TRUE TEMP”…what could possibly go wrong???]
The oven beeps when it has supposedly finished preheating, so I eagerly walked over to the oven when it alerted me. I didn’t want to impact the temperature by opening the door, so I quickly turned on the oven light and bent down to look at the temperature.
The oven temperature read about 290F or so. I can’t quite remember it exactly, but it wasn’t even close! I gave the oven the benefit of the doubt, assuming that it just took longer to preheat.
And I waited some more. The temperature climbed slowly and after a good 15 minutes, I decided it wasn’t moving anymore. I waited an extra 30 minutes just to be sure.
I squinted my eyes really hard (am I getting old or are those things just really tiny?)
To me, it looks about 315-320F:
This is about a 30-35 degree difference. I also tested various places in the oven (on the side and in the back), but they were all around that temperature give or take 5 degrees. I even left it in for a full hour just to be sure. Nada.
Every good researcher knows that it’s to never advisable to rely on a single study, right? So, I headed out and bought another brand of oven thermometer (this time from Canadian Tire) and tested it once again.
Replicate.
Wouldn’t you know it, the temperature was the exact same. Approximately 320 degrees Fahrenheit when it should have been 350. At least the thermometers are accurate. ;)
I Googled if there was any way to fix my wonky oven temperature and it turns out that it’s fairly easy to calibrate many kinds of ovens, depending on the severity.
Always start with the manual first. I looked for the owner’s manual, but wasn’t able to locate one (not surprising being in a rental and all). Eric suggested that we find the model number of our oven and see if we could find instructions online. He wasn’t able to find the manual online for this oven.
Eric finally ended up finding directions on Appliance 411- "How do I adjust the oven temperature on my range?".
Following these directions, he was able to set the oven temperature higher (35F was as high as he could go), however it’s still not a perfect calibration. Now, when I set the oven to 350F, it heats to about 340F, so it’s still about 10 degrees too low. To attain 350F, I have to set the oven to 360F and also wait about 5-10 minutes after the oven tells me it’s preheated. This isn’t a huge deal, as long as I’m careful and I keep my oven thermometer in the oven when using.
The oven thermometer is probably the best solution we have right now, aside from actually paying someone to repair it (or asking the landlord), which I probably wouldn’t bother with unless it got worse.
Our first adventure in oven calibration is now complete.
One thing I love about this oven? The stove top heats up much faster than our old oven back at home. You win some, you lose some! I’ve burned a few veggie burgers so far, but I’ll get used to it eventually.
Have you ever measured your oven’s true temperature or calibrated your oven? I bet you sure are curious now…
My parents got a new oven a couple years back and while I was living there, it was awesome! I’d bake all kinds of cakes, cookies and cupcakes and they turned out perfectly. Now that I’m in a rental condo, it’s a whole different story. First of all, I can’t convection bake anything, which is a HUGE bummer and I’m pretty sure our oven is heating up to a temp lower than is actually says, similar to yours. I have yet to get an oven thermometer to check but now that your post has reminded me, I think I will–especially with wedding season coming up and cupcakes on the horizon.
Wow, good experiment! My oven at my place is totally wacky and sometimes will take WAY longer to cook things than it’s supposed to. The temp is probably way off on it, but at least I know I’m not just imagining it now!
Baking in different ovens is insane – I now! I used to housesit a lot (I mean, a lot) and always had to adapt to cooking in different kitchens. I always use an oven thermometer, even now – and it would seem that slow preheating is a common problem! I always wait far past the time it says it’s ready.
Also, a tip: never leave your oven thermometer in the oven when using the ‘clean’ cycle. I did this once and opened the oven to find my thermometer completely dead – it literally was pale like a ghost, and it failed to work at all. Poor thermometer! RIP
ah that is a great tip and probably easy to overlook. Now I just need to clean this beast…that will be the next project.
Teaching my 9 year old to use the oven, he often looks at me like I’m nuts when I tell him, “see the recipe says 350 so I want you to preheat the oven to 365.” He’s starting to believe me when I show him the oven thermometer inside that is RIGHT ON once the preheat is done. Go Mom. Way to have cred.
love that. He’s probably like…how does she always know everything? heh
Hmmm, very interesting. This makes me want to check my oven, as I am sure it is off.
Oh my gosh!
So true, I never thought I could calibrate my oven!!
Similarly, I moved into a rental that as a VERY wonky oven and have had many frustrating expereinces with it taking a long time to cook something or over cooking it totally.
I am deffinately going to have to do some experimenting!!
Great tip!
ahhh but the problem with electric stove tops is the amount of time they take to cool down! i often found in my old flat that you couldn’t just turn off the heat and leave the pan on the top, because it would just carry on cookin! interesting post!
yea that is true…gotta be careful with them. Im constantly burning things
I have never done this before, but you are right — I am SO curious now! :-) Thinking I will be doing this on Saturday!
Such a beautiful research! Thank you!
I did this last year but of course never thought to blog about it! I found that mine was 20 or so degrees lower than what it should be and did the fancy preset you mentioned to get it up to a higher temp. Great post, Angela!
I remember my mom having a really old oven and it’s always a lot hotter than the temperature she sets it too. She ends up just adjusting all her recipes, but that’s such a great idea to adjust it… I didn’t even know that was possible!
Wow, that is so interesting..thanks for sharing! I have been using our small convection oven a lot lately and I like how it evenly cooks things better than our traditional oven…have an awesome day!!
Wow, thats something I never thought of checking! Great post!
Gotta get me one of these. I am quite sure my oven temp is off. The other challenge I have is that the oven doesn’t seem to hold a constant temp – the heating element goes on continuously even if I let it warm up for 30 plus minutes- so I have to watch closely to ensure the bottom doesn’t burn. Makes bakIng that much more adventurous :)
I honestly didn’t assume that it wouldn’t be correct. Woops!
I know, it’s one of those things that I never thought about either.
My oven is woefully off. After we moved in, trying to find the right temperature was an enormous pain…until we got a thermometer.
Everything comes out so much better when you actually bake at the right temperature!
Glad that things are working out for you!
Thank you, very interesting to read. I think Canadian Tire will soon have a shortage of over thermometer now you have posted this LOL.
I will have to check mine as I’m not always happy about things turn out, especially cakes.
Isa
It is soo smart to test your oven!! I still haven’t done mine, thanks for the reminder!! And your kitchen looks beautiful! :)
Thank you for sharing this! We just moved into a new house a few months ago and I cannot tell you how many recipes I have botched with the new oven. It is gas, which is new to me, and it heats up much higher than the temperatures I set it to. I am going out right now to buy an oven thermo!
goodluck!!
That is so interesting. I would never have thought to even check on something like that, because when the oven says 350 – you assume it’s 350. I’ve been married 33 years and NEVER checked my oven temp before. I will have to do that as soon as I buy a thermometer. Great blog.
Don’t worry I hadn’t checked my previous ovens either…it’s not something that comes to mind often or at all!
I’m really glad you did this experiment. Our oven growing up was always about 50F off (even when brand new), so we’d always just change where we set it. I have always used an oven thermometer to check my oven, but I kind of always wondered if my oven thermometer was trust-worthy – I’m glad to see that with 2 different ones you got accurate measurements. I also never realized that an oven could be calibrated. Huh! Will definitely look into that and consult my oven’s manual (the original owners of our house kept a binder with literally EVERY owner’s manual for everything in the house (including the smoke detectors and the blinds…??), so we even have it after 22 years!)
Also…I’m happy you pointed out that waiting some extra time and not trusting that “I’m ready!” ding is also a part of the “fudge factor” with ovens. Very helpful!
Yes, darling I am no SO very curious! I know I have this one certain cookie recipe that sure is different at my house than from my friends/families houses. I can bet you mine is way off!
Thanks Angela. :)
Have a great Friday.
It’s SO true! We move a lot so I have had a lot of experience cooking in different ovens and the differences in results and cooking times just astounds me every time! Thanks for the post as I never knew how to calibrate it.
Ugh! This explains so much. Thank you, Angela! Your blog is inspiring…still thinking about making those peanut butter cups :)
haha!! from now on, any baked treats that don’t come out right will be blamed on my new oven…teeehee. How interesting about 90 deg.! that IS a huge difference. And omygoodness Angela, I love your kitchen!! So gorgeous and bright. :D
when I was a kid, my parents bought a new custom-built home. of course, new appliances were in the kitchen. and the first meal my mom made us in that oven was burned to a crisp. if i remember correctly we had to order out for pizza because it was just not edible. my dad tried to fix it, to no avail. they had a repair man come out and he got it down to an acceptable level – we had to adjust baking time on *everything* though, even with the repair. Mom cooked/baked/roasted with that oven for well over 20 years, and just got a new oven a couple of years ago. she was so used to that dang over-heated oven that she thought something was wrong with the new one, when in fact, it was just normal!
hah great story :) funny how you get used to things over time right?
We noticed that at different settings it would even be further off. At 350 it was 380. But at 450 it was 500. Ours was awful!
I think mine was doing that too when I tried it at 425…just realized last night that it cooks stuff much quicker in the back then the front. Half my granola was burnt and half was perfect. lol
I’m pretty sure my oven’s off, have always been but am just too lazy to get a thermometer. Your post reminded me. I think I’ll just stick with increasing or decreasing the temperature as needed. The calibration thing sounds difficult!
Thanks so much for posting this. Never thought to test out an oven with an oven thermometer. So glad you posted this!!
I have used a wide variety of ovens with all my moves over the years, and I’ve found that many ovens that are 25+ years old perform better than those that are around 5-10 years. Maybe because people really used their ovens back in the day. It seems that you have to either really work at the newer models, or just shell out a lot of cash to get something decent at this point (I mean, when we moved into our 1950’s house a year or so ago, I was amazed that the huge 6 burner stove from the late 60’s was still performing superbly. . . or course, then an element died, and I couldn’t find a replacement. . .!”
you know what they say…they dont make em like they used to!!
Another aspect to think about is the heating and cooling cycle of the oven. As the heating coil turns on and off the temp fluctuates. My gem of an oven fluctuates +-50 degrees!
yea I have realized mine fluctuates too…made muffins the other day and it went from 330 to 360 I think
because of all the somewhat-shady-yet-beautifully-artsy apartments i’ve managed to dwell in, i consider my oven thermometer my go-to kitchen tool! each apartment got lovelier and lovelier, while each oven got scarier and scarier (and older).
i’ve actually ever had an oven that was spot on with what the dial said, so i always spend the first few days in my new place figuring out just how ‘off’ the oven is, then making a little index card of the proper temps for the oven and slapping i up on the stove or wall directly above the stove. works like a charm ;)
I should definitely get an oven thermometer!
I agree – you have to get to know your oven. Apart from the temperature settings, there are hot & cold spots in most ovens.
If you think that’s bad, check out your measuring jugs.
It’s easiest in grammes/litres – one litre of water weighs 1000 grammes.
Measure out a litre and weigh it – I guarantee it will be way out!
Think of the mess it makes of your recipes!
I had an oven that was far off and had a repairman come in. He found that the oven temp prob had caked/baked on food and when he cleaned it off it worked perfectly.
I recently moved into an apartment. The stove is from like the 1970’s. As soon as I started using the oven I noticed something odd. No matter what temp I set it at, it always got hot and smoky inside. The light near the dial would even turn off as if it had hit a max temperature and tripped a safety shut off. I tried to bake something at 250 and saw my oven temp go out of my thermometer range. I guess 400 is it’s max it records. I didn’t know how to fix the oven, so I went ahead and called to have it repaired. I’m waiting for a replacement part.
You’re lucky! I’ve got a Belling and the oven temperature is all over the place. I’ve been told that 20 degrees out either way is acceptable. Today I was told 30 degrees out is fine and to buy a proper thermometer to use. It measures different temperatures in all parts of the oven and today was only close to what it should be in the top back right-hand corner. Basically if set to 180 degrees there’s no way of knowing whether it’s cooking at 180 or 200 or 160, or anywhere in between. Following the manufacturer’s instructions to reduce the temperature as it’s a fan oven means potentially expecting something to cook while the oven is only 140 degrees. Seems there’s nothing I can do to improve things and any cooking will be pure luck if it comes out cooked properly.
OMG I was just telling my husband that my oven is off by more than 50 degrees and he said no way that I had to be wrong…thank you so much for this, I am def getting a thermometer today no more burned stuff for this house!!
I just recently moved out on my own for the first time. I’m not exactly an expert at baking, but I like to do it here and there as a hobby. Today I burnt my first batch of cookies ever. (At the same time they were horribly undercooked on top.) I did the same thing, and got a thermometer and checked things out. Turns out when I set the dial to 350 it actually went up to 450-460 inside the oven. I tired again and set it at 250 instead, but strangely it still went up to about 400. Hrm. Contacted the manager and landlord about this oven for the 3rd time. The first time we only had one working burner and the second time the oven didn’t even lite.
I just moved into a new apartment and testing my oven temp was the first thing I did. It’s an older oven so I knew it may be off. After preheating to 350, I checked the oven thermometer and “bam!” It was closer to 450! My oven reads almost 100 degrees over! I did this test a few times, using a few different thermometers with the same sad results. I bake and cook a lot so this is a huge disappointment :(
I’d recommend everyone invest in an oven thermometer. Since I’ve been using it, everything taste so much better. No lie, it’s one of the best (kitchen) investments I’ve ever made. What a difference! Thanks for the post about this issue. It’s more important than people think!
Thank you so much for this blog. I use my oven all the time when preparing dinner for my family. We just moved and I soon as I was cooking my first meal I realized my oven wasn’t working like my previous oven. It took so much longer to cook. A meal that normally took 30 minutes ended up taking 50 minutes in this oven. I put up with in for about a 2 month now, but now that I’m trying some new recipes for Easter I figured I better attempt to find a fix so that I don’t under or over cook anything or end up spending more time cooking then necessary. This was a huge help. I went out and purchase a thermometer and sure enough my oven was off by 15F I was only getting to 335 when I set it to 350. I made the adjustments and now my oven is heating up to the correct degrees. Thank you again!!!
The oven in our new house is no more than 2 yrs old.
I felt it was very hot but thought it was because it was a fan oven
And set it lower temperature. But I think that it’s waay too hot still.
A sandwich cake turned out like very laarge biscuits.
The idea of baking white bread slices is very good and I must get an
Oven thermometer!
I was curious too. My thermostat says 270, but my over is set to 300! also, the oven is new. Bummer.
How do u calibrate ur oven temperature?
Digital readout on a GE gas oven, doesn’t go any higher than 290. It is a dial thermostat.
Thank you for this information! I just got a new Whirlpool range and after several experiences of undercooked frozen dinners, I decided to test it at various temperatures, preheating from 20 minutes to an hour. It’s always at least 50-75 degrees lower than it should be. Had the repairman out today and he said nothing’s wrong with it, tests ok, and that the oven thermometers don’t work with the newer ovens. Give me a break. I can guarantee you nothing’s wrong with the oven thermometer. Looking forward to calibrating the oven with your instructions and see if I can get it much closer to the temperature I’ve selected.
Looks like the same make as my brand new oven that is out over 75 degrees and has a non workingm convection. Lol mi even did the same and thought it was a defective Cdn Tire oven thermometer. Wish I had my old coil topmstobr back.
Have an Whirlpool Accu-Bake gas range. After a couple baking disasters and trying not to blame the tool used a digital thermometer.
Observations: When the oven indicates it is up to preheat temperature, it is not. The variation is at least + / – 15 degrees F. So on preheat when the read out indicates the oven is at 350 degrees F it is 335 degrees F. At times the variation is much as +/- 25 degrees F. So a set point of 365 degrees F yields an average oven temperature of about 350 degrees F.
So DON’T put your baking in when the oven indicates it is up to baking temperature. It will spend most, if not all its baking time at least 15 degrees under the set point. That doesn’t take into account the temperature loss when loading the oven.
There must be an oven out there that has a variable rate gas valve to reduce the significant variation +/- of set point! It’s like a car with an off on switch in place of an accelerator pedal. Hard on the souffles….!