An 8-inch cake tin in the recipe, a 20 cm pan in your cupboard: close enough? Start with the sizes below. Eight inches is exactly 20.32 cm, so a 20 cm tin is a little smaller, even though the two are often close choices.
Two different kinds of comparison
“Exact cm conversion” changes the unit, using exactly 2.54 cm per inch.
“Nearby cm size” points to a practical metric pan or adjustable frame setting. It does not mean the same capacity.
— No single metric match is suggested here. Check your pan’s inside measurements. Nearby sizes are reference points, not a universal manufacturing standard.
Square tin sizes vary by manufacturer; an adjustable frame offers more choices. A 22 × 22 cm tin and a 24 × 24 cm tin are two alternatives to compare, not interchangeable sizes.
A 9 × 5-inch pan is often a deep loaf tin; a 10 × 15-inch pan is often a shallower tray. Matching length and width alone does not match their usable capacity.
13×9 in is a US pan size. Its exact metric equivalent is 33.02×22.86 cm; that does not make it a standard European size.
Measure the space the batter fills
Measure inside the pan, wall to wall. Leave out handles and the outer rim. With sloping sides, take separate measurements at the top and bottom before making an exact comparison.
Round: inside diameterSquare: inside side lengthRectangular: inside length × width
Sizes you’ll often see in recipes
US cake recipes frequently call for 8- or 9-inch round and square pans, a 9 × 13-inch rectangular pan, or a larger 10 × 15-inch tray. The other sizes in this baking pan size chart are useful references too, but they are not all equally common.
Metric ranges follow a different pattern: round tins may come in 18, 20, 22, 24, 26, 28 and 30 cm diameters. Square and rectangular sizes vary more between brands. A label is a starting point; your pan’s inside measurements are what matter.
Depth changes the picture
Two tins with the same diameter can hold different amounts if one is deeper. Sloping sides change the space at the bottom as well. For a recipe adjustment, compare the depth of batter you want, not just the height of the rim.
A quick check may be enough
If a recipe calls for an 8-inch round tin and yours is 20 cm with a similar depth, the chart shows that they are close. It helps you judge the substitution; it cannot promise the same cake thickness in every recipe.
Use the converter when…
The pan depth or intended batter depth changes.
You switch between round, square and rectangular pans.
The sides slope.
You want an exact ingredient ratio.
Your size is missing from the chart.
Not quite the same pan? Compare it properly
For a different depth, an unusual size or another shape, enter both pans’ inside measurements. The same pan converter will work out the factor and adjust your ingredients.
Choose a mode
Units
Result units
01 / Pan volume calculator
How much does your pan hold?
Enter the pan’s internal dimensions to find its capacity to the rim or a chosen filling height.
02 / Convert a recipe to another pan
Different pan from the one in the recipe?
Enter the original and new pan sizes, add your recipe, and get the adjusted ingredient quantities.
03 / How much batter for your pan?
Got a recipe, but no pan size?
No need to know which pan the recipe author used. Choose a baking category and enter the ingredients and your pan dimensions.
Supported pan shapesRoundSquareRectangularOvalTriangularStraight and sloping sides
A worked example
At the same batter depth, moving from a round 20 cm pan to a round 24 cm pan takes 1.44 times the recipe. Use the converter when the shape is different too.
Frequently asked questions
Is a 20 cm cake tin the same as an 8-inch pan?
An 8-inch cake tin is exactly 20.32 cm; 20 cm is about 7.87 inches. They are close, but not identical. This cake pan size chart gives a quick comparison; use the converter below when depth or shape also changes.
Can I use a 20 cm pan instead of an 8 inch pan?
They are close, but 8 in is 20.32 cm. At the same batter depth, a 20 cm round pan needs about 3.1% less of the recipe. Use your actual measurements in the converter.
Why doesn’t the guide list pan capacities?
Diameter or base size alone doesn’t tell you the volume. You also need the depth and, for sloping walls, both top and base measurements.
Can I mix inches and centimetres?
Yes. Choose Metric or US as a default, then choose cm, mm or in once per pan card. The original and target pans may use different units; changing the unit preserves their physical size.
Can I use a pan with a centre tube?
Centre tubes, fluting and irregular outlines are not modelled. Measure actual capacity or use a method appropriate to that shape; do not treat an ordinary circle as a tube pan.
Why give both an exact conversion and a nearby size?
Eight inches converts to exactly 20.32 cm. The nearby 20 cm size helps you recognise a metric tin, but it is slightly smaller and does not hold exactly the same amount.
Does the same diameter mean the same volume?
Only if the depth and shape match too. A deep, straight-sided tin and a shallow, sloping-sided tin can have the same top diameter but quite different capacities.
What if my pan isn’t listed?
Measure inside it and compare it with the recipe’s pan in the converter. You can use cm, mm or inches, even different units for the two pans.
Can I swap a round pan for a square one?
Yes, but the diameter of a circle is not equivalent to the side of a square. Compare both shapes and the intended batter depth to get the ingredient ratio.