# Cooks: Preheat vs. start in a cold oven. When? Why?
**URL:** https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367
**Category:** Cafe Society
**Created:** [May 22, 2010, 2:52pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367 "2010-05-22T14:52:46Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)
#### Post date: [May 22, 2010, 2:52pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/1 "2010-05-22T14:52:46Z")
Some recipes for cooking in the oven (okay, the _vast_ majority) tell me to preheat my oven before putting the food in; but some (Alton’s recipe for roasted bacon, for instance) call for putting the food into a cold oven and _then_ firing it up.
What’s the rationale for this? What would happen if, say, I put my batter-filled cake pans into a cold oven and then started it going to 350?
---
### Author:  [@Shawn1767](https://boards.straightdope.com/u/Shawn1767)
#### Post date: [May 22, 2010, 4:26pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/2 "2010-05-22T16:26:28Z")
Just talking off the top of my head here, but I thought that in baking, at least, if you are depending on steam to help with the rise of the batter, you need to start off with a hot oven. You get a good blast of heat to start off with. But again, that’s just something i’ve heard.
---
### Author:  [@JohnT](https://boards.straightdope.com/u/JohnT)
#### Post date: [May 22, 2010, 5:27pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/3 "2010-05-22T17:27:03Z")
I think that for most foods an average American would eat at night, pre-heating doesn’t make much of a difference. For others, say breads and pastries, it will make a difference and should be done.
---
### Author:  [@Fuzzy\_Dunlop](https://boards.straightdope.com/u/Fuzzy_Dunlop)
#### Post date: [May 22, 2010, 5:39pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/4 "2010-05-22T17:39:45Z")
> [@JohnT](#):
>
> I think that for most foods an average American would eat at night, pre-heating doesn’t make much of a difference. For others, say breads and pastries, it will make a difference and should be done.
On the other hand people and cookbooks tend to tell you to cook for a certain length of time rather than a better measure of doneness, like temperature. It’s bad enough to say “cook the meat in a 325 degree oven for 30 minutes” rather than “until its temperature is 165”. If you don`t even start with a 325 degree oven you’re even less likely to get it right.
---
### Author:  [@appleciders](https://boards.straightdope.com/u/appleciders)
#### Post date: [May 22, 2010, 5:41pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/5 "2010-05-22T17:41:14Z")
Plus, while it might not matter for some foods, ovens vary widely and some may heat up much faster.
I can’t think of a good reason to start with a cold oven, actually. Can anyone?
---
### Author:  [@Nefarious\_Chipmunk](https://boards.straightdope.com/u/Nefarious_Chipmunk)
#### Post date: [May 22, 2010, 5:44pm UTC](https://boards.straightdope.com/t/cooks-preheat-vs-start-in-a-cold-oven-when-why/540367/6 "2010-05-22T17:44:59Z")
My oven repair man once explained this to me. As he explained it, if a steady temperature is really important (like with most baking), then you want to preheat the over for at least 15 minutes. He explained that when an oven first heats up, it tends to over heat and then drop down and reheat (oscillating) until the temperature evens out, due to the way that the thermostat works. It takes that amount of time for the heat to even out enough for the temperature to stay pretty constant.
This is based completely on what he said, so take it FWIW.