Cake Pan Converter
Change the pan shape or size and this calculator works out the volume ratio between the original and your pan, the ingredient scaling factor, and how much the batter depth changes. It covers round, square, rectangular, and loaf pans in both metric and imperial units. All results update as you type.
Formula
Worked example
Recipe calls for a 9 in round (area = pi x 4.5^2 = 63.6 sq in). You have an 8 in round (area = pi x 4^2 = 50.3 sq in). Scaling factor = 50.3 / 63.6 = 0.791. Multiply every ingredient by 0.791 (about 80% of the original). Pan depth stays 2 in for both, so batter depth is nearly identical and no temperature or time adjustment is needed.
Why pan area, not pan volume, drives the scaling factor
When you swap pans of the same depth, the key number is base area: it determines how wide the batter spreads. Volume matters too, but bakers typically fill pans to the same depth regardless of diameter, not to the same absolute volume. So the scaling factor for ingredients is always the ratio of base areas. If the pan depths differ significantly, check the batter-depth percentage this calculator shows: a much deeper batter needs lower heat and more time, and a much shallower one needs slightly higher heat and less time.
How the batter depth adjustment works
The calculator multiplies your fill fraction by the original pan height to find the actual batter depth in the original pan, then divides that depth by your pan height to find the new fill fraction. If that new fraction is more than 67% of pan height, the batter is at risk of overflowing or staying wet in the centre; lower the oven temperature by about 25 F (15 C) and extend baking time, testing with a skewer rather than relying on the recipe clock. If the new fraction is below 40%, the batter will be thin and can dry out: raise the temperature slightly and check 10-15 minutes before the recipe end time.
Common pan substitutions that need no adjustment
A 9 in round (63.6 sq in) and an 8 in square (64.0 sq in) are essentially identical in base area and are the most common perfect swap in home baking. Similarly, two 8 in round pans together hold roughly the same batter as one 9 x 13 in rectangular pan, because 2 x 50.3 = 100.6 sq in versus 117 sq in (about a 14% difference, small enough that a light skewer check covers it). The 8 x 8 in square and the 9 in round also pair well, at 64.0 vs 63.6 sq in.
Tips for scaling ingredient quantities
Multiply every ingredient by the scaling factor, including eggs. For eggs, round to the nearest half egg: if the factor is 0.75 and the recipe calls for 4 eggs, use 3 (0.75 x 4 = 3.0 exactly). For factors between 0.9 and 1.1 you can often leave eggs unchanged. Leavening (baking powder, baking soda) scales linearly like everything else, but taste with a finger: slightly under-scaled leavening in a larger recipe is usually preferable to a gummy centre from too much. For very small batches (factor under 0.5), consider whether halving the recipe outright is simpler than measuring fractions.
Standard baking pan sizes and volumes
| Pan | Dimensions | Base area (sq in) | Volume (cups) | Volume (litres) |
|---|---|---|---|---|
| Round | 6 x 2 in | 28.3 | 4 | 0.9 |
| Round | 8 x 2 in | 50.3 | 6 | 1.4 |
| Round | 9 x 2 in | 63.6 | 8 | 1.9 |
| Round | 10 x 2 in | 78.5 | 10-11 | 2.4 |
| Square | 8 x 8 x 2 in | 64.0 | 8 | 1.9 |
| Square | 9 x 9 x 2 in | 81.0 | 10 | 2.4 |
| Rectangular | 9 x 13 x 2 in | 117.0 | 14-15 | 3.3 |
| Rectangular | 7 x 11 x 2 in | 77.0 | 10 | 2.4 |
| Loaf | 8 x 4 x 2.5 in | 32.0 | 4 | 0.9 |
| Loaf | 9 x 5 x 2.5 in | 45.0 | 8 | 1.9 |
| Springform | 9 x 2.5 in | 63.6 | 10 | 2.4 |
| Bundt / tube | 10 x 3 in | ~78 | 10-12 | 2.8 |
Common pan dimensions with approximate batter capacity. Fill pans 50-67% full.
Frequently asked questions
Can I use the same baking time when I change pan size?
Often not exactly. Baking time depends mainly on how deep the batter sits, not on the total volume. If your pan has the same depth as the recipe pan and you have scaled the ingredients correctly, the batter depth should be similar and the time will be close. If your pan is shallower, the batter spreads thinner and bakes faster; if deeper, it needs longer. Use the batter depth change output from this calculator as your guide, and always finish with a skewer test.
What is the scaling factor and how do I apply it?
The scaling factor is the ratio of your pan base area to the original pan base area. Multiply every ingredient in the recipe by this number. For example, a factor of 0.79 means you use 79% of each ingredient. A factor above 1.0 means you need more batter to fill the wider pan to the same depth. Apply the factor to all ingredients including eggs, sugar, flour, butter, milk, and leavening.
Does a round pan and a square pan of the same dimension hold the same batter?
No. A 9 in round pan has a base area of about 63.6 sq in (pi x 4.5 squared), while a 9 in square pan is 81 sq in. The square pan holds about 27% more batter. However, an 8 in square (64.0 sq in) is nearly identical to a 9 in round (63.6 sq in), which is the most useful swap in home baking.
How do I convert a round recipe to a rectangular pan?
Enter the round pan dimensions as the original and the rectangular pan as your pan. The calculator will compute the scaling factor for ingredients. A 9 in round recipe scales to a 9 x 13 in rectangular pan with a factor of about 1.84, meaning you need roughly double the batter. The 9 x 13 is better matched to two 9 in rounds (combined 127 sq in vs 117 sq in, a 9% difference).
What fill level should I use?
Most recipes are designed to fill the pan between half (50%) and two-thirds (67%) full. Dense batters like pound cake are typically filled to 50-55%; lighter sponge batters can go to 60-67%. Never fill above 75%: the batter will overflow or dome excessively. If your scaling factor produces a fill level above 70% in your pan, use the next size up or divide the batter into two pans.
My scaling factor is very small (below 0.5). Should I just halve the recipe?
Yes, if the factor is 0.5 or close to it, halving is simpler and more reliable than multiplying every ingredient by an odd decimal. For factors below 0.5, consider whether the small quantity of batter suits your pan and mixer. Very small batches can be tricky: eggs are hard to divide precisely, and there may not be enough mass in the bowl for your mixer to beat properly.
Do I need to adjust the oven temperature when changing pans?
Only when the batter depth changes noticeably. If you move to a pan where the batter will sit more than 15% deeper than in the original pan, reduce the oven temperature by 25 F (15 C) so the outside does not set before the centre cooks. If the batter will be more than 15% shallower, increase temperature slightly. For most common pan swaps where depth is similar, no temperature change is needed.