Baking Pan Size Converter
Baking in a different tin from the recipe? Pick both pans and see how much bigger or smaller yours is, and how much to multiply each ingredient by.
Paste the recipe's list. Fractions are fine: 1 1/2, 1½, ⅓ or 0.75. Lines without a number stay as they are.
How your pan size is converted
Compare the two pans, then multiply every ingredient by the difference.
- 1
Recipe pan area
π × 4²= 50.27 sq in
- 2
Your pan area
9 × 13= 117 sq in
- 3
Divide the two
117 ÷ 50.27= × 2.33
- 4
Scale each ingredient
1.5 cups × 2.33= 3½ cups
Read more: the formula, a worked example, common pan sizes and baking time
The formula
round pan area = π × (diameter ÷ 2)²
square pan area = side × side
rectangle or loaf area = width × length
scale factor = your pan's area ÷ the recipe pan's area
new amount = recipe amount × scale factor
by volume: volume = area × depth (or the bundt pan's capacity),
scale factor = your pan's volume ÷ the recipe pan's volume
Both pans must use the same unit before you divide; the converter turns everything into cm and cm² first, so you can mix inches and cm. 1 inch = 2.54 cm, so 1 sq in = 6.4516 cm² and 1 cubic inch = 16.387 ml.
Worked example
The recipe is for an 8-inch round pan and you have a 9 × 13 inch pan.
- Recipe pan: radius 8 ÷ 2 = 4 in, area 3.1416 × 4 × 4 = 50.27 sq in (324.3 cm²).
- Your pan: 9 × 13 = 117 sq in (754.8 cm²).
- Scale factor: 117 ÷ 50.27 = 2.33, about 2⅓. Your pan is 133% bigger.
- Without scaling, the batter would be 50.27 ÷ 117 = 0.43 of the depth, a very thin layer.
The sample cake list in Advanced, multiplied by 2.33 and rounded to kitchen fractions:
- 1½ cups flour × 2.33 = 3.49 → 3½ cups
- 1 cup sugar × 2.33 = 2.33 → 2⅓ cups
- ½ cup butter × 2.33 = 1.16 → 1⅛ cups
- 2 eggs × 2.33 = 4.66 → 4 eggs plus about 33 g of beaten egg (0.66 × 50 g)
- ¾ cup milk × 2.33 = 1.75 → 1¾ cups
- 1½ tsp baking powder × 2.33 = 3.49 → 3½ tsp
- ¼ tsp salt × 2.33 = 0.58 → ⅝ tsp
- 1 tsp vanilla × 2.33 = 2.33 → 2⅓ tsp
Common pan sizes
Sizes are measured across the inside of the top. Real pans vary a little by brand, so measure yours if it matters.
| Pan | Area | vs 8-inch round |
|---|---|---|
| 8-inch round (20 cm) | 50.27 sq in | × 1 |
| 9-inch round (23 cm) | 63.62 sq in | × 1.27 |
| 8-inch square (20 cm) | 64 sq in | × 1.27 |
| 9-inch square (23 cm) | 81 sq in | × 1.61 |
| 9 × 5 inch loaf | 45 sq in | × 0.9 |
| 9 × 13 inch (23 × 33 cm) | 117 sq in | × 2.33 |
| 20 cm round | 314.16 cm² | × 0.97 |
| 23 cm round | 415.48 cm² | × 1.28 |
| 20 × 20 cm square | 400 cm² | × 1.23 |
| 23 × 33 cm | 759 cm² | × 2.34 |
An 8-inch round pan is 324.3 cm², so a 20 cm round (314.16 cm²) is 0.97 of it: close enough to swap. Bundt pans are sold by capacity, often 10 or 12 cups. One US cup is 236.6 ml.
Baking time and depth
There is no exact formula for the new baking time. Scaling by area keeps the batter the same depth, so the time is usually close to the recipe's, though a much bigger pan can take a little longer. Deeper batter usually needs longer, and a thinner layer bakes faster. Keep the oven at the recipe's temperature (some bakers lower it a little for deep pans), start checking early, and use the recipe's own test. Most cake pans are filled about half to two-thirds full.
For a whole recipe tool with servings, one-ingredient scaling and cup sizes, see the recipe scaler. For grams and cups, use the cups to grams converter.
Common questions
How do I convert a recipe to a different pan size?
Work out the area of the base of both pans, then divide the new area by the old one. That number is the scale factor: multiply every ingredient by it. An 8-inch round pan is 50.27 sq in and a 9 × 13 inch pan is 117 sq in, so the factor is 117 ÷ 50.27 = 2.33. This keeps the batter the same depth.
Can I use a 9-inch round pan instead of an 8-inch square?
Yes. A 9-inch round pan is 63.62 sq in and an 8-inch square pan is 64 sq in, so they are almost the same (factor 1.006). Use the recipe as written and check it a few minutes early.
How do I work out the area of a round cake tin?
Area = π × radius × radius, where the radius is half the diameter. A 20 cm round tin has a radius of 10 cm, so its area is 3.1416 × 10 × 10 = 314.16 cm². Measure across the inside of the top edge.
How do I convert a recipe for a bundt pan?
Bundt and tube pans are hard to measure, so compare volumes instead. Fill the pan to the brim with water, measure it in cups or litres, and compare with the other pan's volume (length × width × depth, or π × radius² × depth). Turn on Advanced and pick "Bundt or tube" to do this.
Does baking time change with pan size?
Usually, yes, but there is no exact rule. Deeper batter needs longer, and a thin layer bakes faster. Keep the oven temperature the same (some bakers lower it a little for deep pans), start checking early, and use the recipe's own test, like a clean skewer.
What if the scale factor gives part of an egg?
Beat the extra egg and add part of it by weight. A large egg is about 50 g out of its shell (typical), so 0.66 of an egg is about 33 g. If it is close to a whole egg, just round.
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