It's the Heat

• The single likeliest reason for cakes to not bake in time is your oven's thermostat. Generations of cooks have learned to cope with an oven that runs fast or slow, which is a kind way of saying its temperature control is off. Go to your local department store or kitchenware store and buy a pair of inexpensive oven thermometers, and place them at different points in your oven. Set the oven for 350 degrees Fahrenheit, and let it warm for 30 minutes before checking your thermometers. Change the settings and watch your thermometers until you've learned where you have to set the dial to get the correct real temperature. Alternatively, have a technician recalibrate the oven so its thermostat is more accurate.

It's Too Wet

• A cake batter starts out liquid, and finishes as a solid yet moist finished product. Some of that moisture is absorbed by the cake's flour as it bakes, but much of it simply evaporates as steam. If your recipe contains too much liquid -- either because of a typo, or because it wasn't tested well enough -- it will take longer than it should for all that extra moisture to escape. If you have a kitchen scale, you can check the proportions easily enough. Most recipes use approximately equal amounts of flour, sugar and liquids by weight. If your liquids, including your eggs, weight significantly more than the flour or sugar, your recipe is at fault.

Pan Size

• The depth and size of your pans also has a bearing on baking time. Loaf pans take longer to bake the same quantity of batter than shallow round or square pans because flat pans offer more surface area and can absorb heat and shed moisture more quickly. Tube pans and Bundt pans account for this by letting hot air pass through a central chimney, cooking the cake from the middle as well as the edges. If you're baking a large cake on a sheet pan or a professional cake pan, you can help the middle cook by using a heating core -- a funnel-shaped piece of metal -- which conducts heat into the batter and provides more even baking.

Check Your Assumptions

• If you aren't an experienced baker, another possibility is that your cake is done but you don't realize it. Most recipes suggest testing the cake by inserting a toothpick or cake tester and pronouncing the cake finished if it comes out clean. That's true if you use a smooth metal cake tester, but a toothpick or bamboo skewer often has distinct crumbs on it when it leaves the cake. This is normal, and simply means your cake hasn't gotten overdone and dry. Uncooked batter, not crumbs, is the sign of an underbaked cake. Verify the results of your cake tester by eye, nose and fingertip. If the cake looks baked and smells baked, is beginning to pull away from the pan and feels firm when you tap it lightly, it's done.