Baking is chemistry — keep the ratios intact and adapt the pan and oven to match.
Baking is the one place casual scaling can genuinely fail. The ratios between flour, liquid, fat, sugar, eggs and leavening give baked goods their structure, so when you resize a baking recipe the goal is to keep those ratios intact while adapting the pan and oven to match.
The most useful idea in baking math is that the pan controls how your batter bakes. A given batter wants to bake at roughly the depth the author intended: too shallow and it dries out, too deep and the outside sets before the middle. So when you scale, you’re really choosing a pan that keeps a similar depth — compare pans by area, not width. Our Pan Size Converter does this for you.
Baking soda and powder scale with the batter, but they’re so potent that a careless heaping scoop on a bigger batch adds far too much, leaving a metallic taste or a cake that rises fast and collapses. Level every spoon.
In baking, eggs bind and lift, so oddly scaled eggs matter more than in cooking. Beat a whole egg and measure: about 3 tablespoons per large egg, so half is 1½ tablespoons.
Keep the oven temperature the same when you scale and adjust the time instead. A shallower bake can be done 20–30% sooner; a deeper one takes longer and risks a raw center — better to split into two pans. Judge doneness with a toothpick or thermometer, not the original clock.