Cake Batter Calculator

How the calculator works

The calculator does two things. First it works out how much your pan holds, from its measurements. That part is geometry:

round pan: volume = 3.1416 x radius x radius x depth

square or rectangular pan: volume = length x width x depth

With the measurements in inches, the volume comes out in cubic inches. One US cup is 14.44 cubic inches, so dividing by that gives cups.

Then it applies the fill level. King Arthur Baking’s guidance for creamed-butter cakes and one-bowl oil cakes is to fill the pan half to two thirds full:

batter = pan volume x 1/2, up to pan volume x 2/3

So you get a range. The low end is a comfortable fill. The high end is the limit.

Worked example

A 9 inch round pan, 2 inches deep.

1. Radius: 9 / 2 = 4.5 inches.
2. Volume: 3.1416 x 4.5 x 4.5 x 2 = 127.2 cubic inches.
3. In cups: 127.2 / 14.44 = 8.8 cups to the brim.
4. Half full: 8.8 x 1/2 = 4.4 cups.
5. Two thirds full: 8.8 x 2/3 = 5.9 cups.

King Arthur Baking gives the same pan as about 128 cubic inches, or 8.8 cups, so the geometry matches the published figure. Its separate advice that a layer pan should take no more than about 5 to 6 cups of batter matches the top of the range.

A 9 x 13 inch pan, 2 inches deep: 9 x 13 x 2 = 234 cubic inches, which is 16.2 cups. Half to two thirds is 8.1 to 10.8 cups. The published guidance for that pan is no more than 12 cups, with 10 cups safer.

Does my recipe fit?

The useful direction is usually the other way round: you have a recipe and want to know which pan it suits.

King Arthur Baking says a standard cake recipe written for a 9 x 13 inch pan, two 9 inch rounds or three 8 inch rounds makes about 6 cups of batter. Check that against the chart:

• Two 9 inch rounds take 4.4 to 5.9 cups each. Six cups split in two is 3 cups each, a little under half full, which gives two modest layers.
• A 9 x 13 inch pan takes 8.1 to 10.8 cups. Six cups is under half, which is why sheet cakes from a standard recipe come out shallow.
• One 9 inch round takes at most 5.9 cups. All 6 cups will not fit safely. Bake the rest as cupcakes.

If you do not know how much batter a recipe makes, pour it into a large measuring jug before it goes in the pans, or weigh the bowl empty and full.

Pans that hold the same

Two pans with the same volume can stand in for each other. The clearest pair in the source is the 9 inch round and the 8 inch square. At 2 inches deep, the round holds 127 cubic inches and the square 128. King Arthur Baking says they can be swapped without issue.

Other pairs are further apart than they look. An 8 inch round holds 100.5 cubic inches against 127.2 for a 9 inch round. One inch of diameter is a fifth less volume. The source makes the same point: the difference in volume is bigger than the difference in diameter suggests, because a pan has three dimensions.

Depth matters as much as width. A 9 inch springform with 3 inch sides holds about 13 cups, against 8.8 for a 9 inch pan that is 2 inches deep. Enter the true depth of your pan, measured inside.

Using a smaller or larger pan than the recipe says

The source gives bake time guidance for both cases.

A smaller pan. Do not fill it beyond two thirds. Expect the cake to take 10 to 15 minutes longer, and to dome more.

A larger pan. The batter is shallower, so it bakes faster. Start checking 10 to 15 minutes before the time the recipe gives. If the pan is much larger, scale the recipe up instead.

King Arthur Baking’s general rule is that a slightly larger pan is the safer mistake. Too much batter in a small pan risks overflow and a dry cake.

To scale a recipe from one pan to another, the baking pan size converter on this site gives the multiplier.

Cakes this does not suit

The half to two thirds rule is for creamed-butter cakes and one-bowl oil cakes. Chiffon, angel food and sponge cakes need the most height to rise, and the source describes them as poor candidates for pan swaps. Use the pan the recipe names.

Bundt pans are a different case as well. Their stated size is the capacity to the brim, and the bakeable capacity is much less: King Arthur Baking puts a 10 cup Bundt pan at about 6 cups of batter. The calculator cannot work out a Bundt pan from its width, because of the shape.

Tips and common mistakes

Measure the inside of the pan. Width across the top, inside the rim, and depth straight up the side. A “9 inch” pan is not always 9 inches inside.

Measure the depth. A pan that is 1 1/2 inches deep, not 2, holds a quarter less.

Use the low end of the range for a batter that rises a lot.

For two layers, divide the batter by weight. Put each pan on the scale so the layers bake at the same rate and finish the same height.

Check early in a larger pan and allow longer in a smaller one. The source’s figure is 10 to 15 minutes either way.