Doubling a Recipe Does Not Double the Cook Time

You doubled your favorite banana bread. The recipe said 60 minutes at 350°F. So 120 minutes, right? No. Two hours later you have a brick. The math you used works for ingredients. It does not work for time.

Why time does not scale with volume

Heat travels through food from the outside in. The thicker the food, the longer the heat takes to reach the center. But the relationship is not linear. Doubling the volume only adds about 25 to 30 percent to the cook time because the surface area still does most of the work.

Think of it like a bathtub. Filling a tub twice as big does not take twice as long if you also use a bigger hose. The oven is the hose; the food is the tub. The surface area scales, just slower than the volume.

The two ways to bake a doubled batch

Option A: Two pans of the original size

Split the doubled batter between two pans the same size as the recipe used. Bake both at once. The cook time stays the same as the original. This is the safest method, especially for cakes and breads.

Option B: One larger pan

Pour all the doubled batter into a pan with twice the area (or close to it). The cook time goes up by 25 to 30 percent. The risk: the outside dries out before the inside cooks. To help, drop the oven temperature by 25°F and bake longer, so the heat gets in more evenly.

Foods where you should NOT double cook time

• Cookies. Same temperature, same time, just more sheet pans. Bake in batches.
• Muffins and cupcakes. Same time, just two pans.
• Roast chicken or turkey. Cook time is determined by weight (about 13 minutes per pound at 350°F), not the recipe number.
• Pies. Same time. Double the pie means baking two pies side by side.

Use a thermometer, always

Internal temperature beats timing on any large bake. Quick breads and most cakes are done at 200 to 210°F in the center. Yeast bread is done at 190 to 200°F. Chicken is done at 165°F. The thermometer ends the guessing.