Does cooking more than one thing in the oven take longer?

Question

Ex: Cooking 2 pizzas (same temp/time needed) in the oven at the same time. Can I just set the same temperature and time as cooking one, and they’ll both come out perfect still? Why or why not? (Let’s ignore differences in cooking based on which rack the pizza is on lol)

I don’t cook much lol, so I’m trying to wrap my head around how cooking “consumes(?)” heat energy. More food mass isn’t going to *reduce* the temperature in the oven or anything… is it? And, the food masses aren’t connected, so not sharing heat distribution(?), so that seems like they shouldn’t affect each other?

In: Physics

Answer 1

Soo, it kind of depends.

The main limit on how quickly your oven heats things up is heat *transfer*. The transfer of heat from the air in the oven to food is pretty slow. Your oven should be able to generate heat a lot faster than a pair of pizzas, or most other things you’re likely to put in there, can absorb.

*However* there are two important exceptions.

First: steam. Steam *will* absorb a lot of heat from the air. Your pizzas heat up, they generate steam, this steam sucks heat from the air in the oven. (Whereas if you were baking cookies, this won’t be a problem.) Just to confuse things, this can potentially make stuff cook *faster* but at a lower temperature – because that steamy air is also better at transferring heat to whatever’s in your oven.

That’s not what you want for a pizza though. You might notice a pizza on the top shelf browns more slowly (browning needs high temperatures), or even comes out a little soggy. (I’d recommend a higher temperature for two pizzas than you’d use for one. Sometimes it can be worth opening the oven door briefly during cooking to let some steam out, even though this lets cold air in, and perhaps swapping them round mid-cooking.)

Second, putting more stuff in your oven affects the air circulation. The details of this will depend on your oven and what you put in there, but you might make it hard for hot air to evenly reach everything you put in there. (Eg. if you put your pizzas on two large baking trays.)