Height can be a disadvantage if you live in a place with low door frames, but usually it's a good thing. That's certainly true if you're baking cakes, which are always more impressive when they're light, high and fluffy. Boxed cake mixes make high-rising cakes a pretty easy target, but occasionally you might find that your trusty mix lets you down and turns out a disappointingly flat cake. There are a lot of reasons that might happen, and just as many ways to boost the height of your cakes.
Get an Oven Thermometer
Before you make any other adjustments, the first thing you should do is buy yourself an oven thermometer. The thermostat that's built into your oven is usually not completely accurate, which is why some seem to run hotter than others, even when they're set for the same temperature. With a separate oven thermometer, you can test your oven and see what the temperature really is at any given setting. You may need to raise or lower it to get the temperature you actually want. Some ovens have hot spots, too. You can learn where those are by filling a couple of large sheet pans with breadcrumbs and baking them for a few minutes. The pattern of pale and dark, toasty breadcrumbs will tell you pretty quickly where your problem areas are.
Follow the Instructions
This may sound like snark, but it's not: Follow the instructions as written. Cake mixes need to be beaten for a certain length of time to whip air into them, which is where a lot of their height comes from. You'd be surprised how long two minutes feels when you're standing over a mixing bowl, so you might have to set a timer on your phone to make sure you keep going for long enough. You should also hold off on any additions or substitutions, like a pudding mix or a dollop of mayonnaise. Sometimes those can make your cake denser.
Add Some Leavening
Another obvious way to make your cake rise higher is by adding some leavening. There are different ways to do this. One is by adding a small amount of baking powder, perhaps 1/4 teaspoon, to the dry mix before you add the liquid ingredients. You might also add meringue powder or an extra egg, which will help lighten the mixture. Another option is to separate your eggs and whip the whites separately, then fold them into the batter after it's mixed. The egg whites lift the cake, like they do in a sponge cake.
Make Enough Batter
Some box mixes can be a bit skimpy when you're using larger pans. If your finished batter doesn't come at least halfway up the sides of the pan, it's going to be pretty flat when it's done. With some batters, you can even go as high as 2/3 of the way up the side of the pan. If you're unsure, a lot of baking sites have pan size conversion charts that tell you how many cups of batter you'll ideally need for any pan. If your mix makes less than that, you might need to use a box and a half to get a nice, high cake.
Keep the Batter From Setting
Sometimes your cake doesn't reach its full potential height just because the outer edges set too quickly, limiting how much the cake can rise. You can try turning down your baking temperature by 15 to 25 degrees, and baking it longer to compensate. You might also find you get better results by wrapping your pan with insulated baking strips. These keep the batter at the sides from hardening so quickly, which – especially at the edges – lets it rise higher. As a bonus, your cake will be more level, without a big dome in the middle that needs to be trimmed off. It also helps if you don't grease the sides of your pan. Have you ever tried to climb a greased pole? It's the same here: Your batter can rise farther up the side of the pan if it's not slipping away.