Free Cake Tin Size Converter – Adjust Your Baking Recipes
Have you found the perfect cake recipe but don’t have the correct-sized baking tin?
Perhaps your recipe calls for a 20 cm round cake tin, but you only have a 23 cm tin. Or maybe you want to bake a square cake using a recipe designed for a round tin.
Our free Cake Tin Size Converter helps you calculate how much cake mixture you need when changing the size or shape of your baking tin.
Simply enter the dimensions of your original cake tin, select the size of the tin you want to use, and the calculator works out how much to increase or decrease your ingredients.
You can convert between round, square and rectangular cake tins, using centimetres or inches. Go To Calculator
What Is a Cake Tin Size Converter?
A Cake Tin Size Converter is an online baking calculator that helps you adjust ingredient quantities when using a different-sized cake tin.
Cake recipes are generally designed for a particular tin size. Changing that size can affect the thickness of the cake mixture, baking time and finished cake. Continue reading
Cake Tin Size Converter
Resize your cake recipe for a different baking tin
1. Original recipe tin
2. New cake tin
For round tins, enter the diameter. For square tins, enter one side. For rectangular tins, enter width and length. Optional batter depths must use the units selected for their respective tins.
3. Scale your ingredients
Enter the quantities from your original recipe. Results update when you calculate.
What Is a Cake Tin Size Converter?
A Cake Tin Size Converter is an online baking calculator that helps you adjust ingredient quantities when using a different-sized cake tin.
Cake recipes are generally designed for a particular tin size. Changing that size can affect the thickness of the cake mixture, baking time and finished cake.
For example, if a recipe is designed for a 20 cm round cake tin but you want to use a larger 23 cm round tin, you will need more mixture to achieve approximately the same cake depth.
Our cake tin conversion calculator compares the surface areas of the two tins and calculates an ingredient scaling factor.
It can also account for different batter depths when you enter those measurements.
This makes it easier to adapt cake recipes without having to calculate the quantities manually.
How to Use Our Cake Tin Size Converter
Our free calculator is designed to make cake tin conversions straightforward.
Step 1: Select Your Original Cake Tin Shape
Start by choosing the shape of the tin specified in your recipe.
You can select:
Round cake tin
Square cake tin
Rectangular cake tin
Step 2: Enter the Original Tin Dimensions
Enter the dimensions of the tin used in the original recipe.
For round tins, enter the diameter.
For square tins, enter the length of one side.
For rectangular tins, enter the width and length.
You can choose either centimetres or inches.
Step 3: Enter Your New Cake Tin Size
Next, select the shape and dimensions of the cake tin you intend to use.
For example, you might be changing from a 20 cm round tin to a 23 cm round tin.
You can also convert between different shapes, such as a round tin and a square tin.
Step 4: Adjust for Batter Depth if Necessary
If you want the finished cake to have a different depth, enter the original and desired batter depths.
If you want to maintain the same batter depth, leave both fields blank.
Step 5: Calculate Your Ingredient Quantities
Click Calculate Conversion.
The calculator will display:
The ingredient multiplication factor
The percentage increase or decrease required
The surface areas of the original and new tins
Adjusted ingredient quantities when you enter your recipe ingredients
You can then use the results to prepare the correct amount of cake mixture.
Cake Tin Size Conversion Chart
The following table shows approximate ingredient adjustments when converting between common round cake tin sizes.
All calculations assume the same depth of cake mixture.
| Original Round Tin | New Round Tin | Ingredient Multiplier | Adjustment |
|---|---|---|---|
| 15 cm | 18 cm | 1.44× | Increase by 44% |
| 18 cm | 20 cm | 1.23× | Increase by 23% |
| 20 cm | 23 cm | 1.32× | Increase by 32% |
| 20 cm | 25 cm | 1.56× | Increase by 56% |
| 23 cm | 20 cm | 0.76× | Decrease by 24% |
| 25 cm | 20 cm | 0.64× | Decrease by 36% |
| 20 cm | 15 cm | 0.56× | Decrease by 44% |
These figures are rounded for convenience. Use the calculator above for a more precise result.
How Do You Calculate Cake Tin Size Conversions?
Cake tin conversions are based on comparing the surface areas of the original and replacement tins.
When you maintain the same depth of cake mixture, the amount of batter required is approximately proportional to the area of the tin.
The formula is:
Ingredient Multiplier = New Tin Area ÷ Original Tin Area
For a round cake tin, the area is calculated using:
Area = π × (Diameter ÷ 2)²
For a square cake tin:
Area = Side Length × Side Length
For a rectangular cake tin:
Area = Length × Width
If the batter depth also changes, the multiplier must be adjusted by the ratio of the new depth to the original depth.
Our Cake Tin Size Converter performs these calculations automatically.
Example: Converting a 20 cm Round Cake Tin to a 23 cm Round Tin
Suppose you have a Victoria sponge recipe designed for a 20 cm round cake tin.
Your recipe requires:
200 g self-raising flour
200 g caster sugar
200 g butter
4 eggs
You want to bake the cake in a 23 cm round tin while maintaining approximately the same depth.
The conversion factor is:
(23 ÷ 20)² = 1.3225
This means you need approximately 32% more cake mixture.
Your adjusted recipe becomes:
| Ingredient | Original Quantity | New Quantity |
|---|---|---|
| Self-raising flour | 200 g | 264.5 g |
| Caster sugar | 200 g | 264.5 g |
| Butter | 200 g | 264.5 g |
| Eggs | 4 | 5.29 |
In practice, you could round the weighed ingredients sensibly and weigh beaten eggs to obtain a more accurate quantity.
Remember that cake recipes can be sensitive to changes in ingredient ratios, particularly when raising agents are involved.
Converting a Round Cake Tin to a Square Tin
Round-to-square cake tin conversions are particularly useful when you want to change the presentation of a cake.
For example, you may have a recipe for a round Victoria sponge but want to bake a square cake for easier slicing.
A square tin generally has a larger surface area than a round tin with the same stated width or diameter.
This means you may need more cake mixture to achieve the same depth.
Example: 20 cm Round Tin to 20 cm Square Tin
A 20 cm round tin has an area of approximately 314 cm².
A 20 cm square tin has an area of 400 cm².
The ingredient multiplier is:
400 ÷ 314.16 ≈ 1.27
You therefore need approximately 27% more cake mixture for the square tin.
Our calculator makes this conversion easy without needing to work out the surface areas yourself.
Can You Use a Different Cake Tin Size Without Changing the Recipe?
Sometimes, but the results may be different.
If you use the same amount of mixture in a larger tin, the cake will generally be shallower.
If you use the same amount of mixture in a smaller tin, the cake will generally be deeper.
This can affect the baking time and how evenly the cake cooks.
A shallower cake may bake more quickly, while a deeper cake may require longer in the oven.
However, baking times cannot be reliably calculated from tin size alone.
For more consistent results, it is usually better to adjust the ingredient quantities to suit your chosen tin, particularly when the size difference is substantial.
Does Changing Cake Tin Size Affect Baking Time?
Yes. Changing the size or depth of a cake can affect how long it needs in the oven.
Several factors influence baking time.
Cake Depth
A deeper cake may take longer for heat to reach the centre.
Cake Tin Material
Metal, glass and silicone baking tins can transfer heat differently.
Oven Type
Fan ovens and conventional ovens may require different temperature settings.
Cake Recipe
Dense fruit cakes, sponge cakes, chocolate cakes and cheesecakes can behave differently when baked in larger or smaller tins.
Oven Temperature
Always follow the recipe’s temperature guidance initially and monitor the cake carefully.
A skewer inserted into the centre can be useful for checking many sponge cakes, although some recipes require different doneness tests.
Important: The Cake Tin Size Converter calculates ingredient quantities. It does not automatically determine a new baking time or oven temperature.
Common Cake Tin Sizes in the UK
Cake tins are available in a variety of sizes, but several measurements are particularly common in British baking recipes.
| Metric Size | Approximate Imperial Size |
|---|---|
| 15 cm | 6 inches |
| 18 cm | 7 inches |
| 20 cm | 8 inches |
| 23 cm | 9 inches |
| 25 cm | 10 inches |
| 28 cm | 11 inches |
| 30 cm | 12 inches |
These are convenient rounded equivalents rather than exact conversions.
For example, 8 inches is exactly 20.32 cm, not 20 cm.
Our calculator supports both centimetres and inches, allowing you to enter the measurements shown on your recipe or baking tin.
Tips for Successfully Changing Cake Tin Sizes
1. Measure Your Cake Tin Correctly
For round tins, measure the internal diameter across the top of the tin.
For square and rectangular tins, measure the internal length and width.
Avoid including the thickness of the tin walls.
2. Consider the Depth of Your Tin
Make sure your chosen cake tin is deep enough to hold the adjusted mixture safely.
Avoid overfilling it, as the cake may rise above the sides during baking.
3. Use Kitchen Scales
Digital kitchen scales make it easier to measure adjusted ingredient quantities accurately.
This is particularly useful for baking recipes where precise proportions matter.
4. Be Careful with Eggs
Scaling a recipe can produce fractional egg quantities.
For example, a recipe might require 3.6 eggs after conversion.
For greater accuracy, beat the eggs together and weigh out the required proportion.
5. Monitor Baking Time
Start checking your cake at an appropriate point rather than assuming the original baking time will still be correct.
6. Consider Baking in Multiple Tins
If your new cake requires considerably more mixture, it may be easier to divide the mixture between two tins rather than baking one very deep cake.
Frequently Asked Questions About Cake Tin Sizes
What size cake tin can I use instead of an 8-inch round tin?
An 8-inch round tin is approximately 20.32 cm in diameter. You can use another size, but you may need to adjust the recipe quantities. Enter the original and replacement tin dimensions into our calculator to find the appropriate multiplier.
Can I convert a round cake recipe to a square tin?
Yes. Our calculator compares the areas of round and square tins and adjusts the ingredient quantities to maintain approximately the same cake depth.
How much more cake mixture do I need for a 9-inch tin instead of an 8-inch tin?
Assuming both tins are round and you want the same cake depth, you need approximately 27% more mixture.
Can I use a rectangular tin instead of a round tin?
Yes. Enter the dimensions of your original round tin and your new rectangular tin. The calculator will determine the ingredient adjustment.
Does the height of the cake tin matter?
Yes. The tin must be deep enough to accommodate the mixture. If you also want to change the depth of the cake itself, you can enter both batter depths into our calculator.
Will I need to change the oven temperature?
Not necessarily. A change in cake tin size does not automatically require a different oven temperature. Follow your recipe’s guidance and make adjustments where appropriate for the cake and oven.
Does the calculator convert inches to centimetres?
Yes. You can enter cake tin dimensions in either centimetres or inches. The calculator converts the measurements internally when comparing the tin sizes.
Is the Cake Tin Size Converter free?
Yes. Calculator Central’s Cake Tin Size Converter is free to use, with no registration required.
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Convert Your Cake Tin Sizes with Confidence
You don’t need to abandon a cake recipe simply because you have a different-sized baking tin.
Our free Cake Tin Size Converter helps you calculate the ingredient adjustments needed for round, square and rectangular cake tins.
Whether you’re baking a Victoria sponge, chocolate cake, birthday cake or celebration cake, the calculator provides a practical starting point for adapting your recipe.
Enter your original cake tin dimensions, choose your replacement tin and calculate the adjusted ingredients using the tool above.