Cake Tin Size Converter

Last updated: June 2026

Original tin shapeOriginal tin size

New tin shapeNew tin size

Original ingredient

g/ml

Area ratio

1.322x

Adjusted amount

661.2 g/ml

Formula

round area = pi x radius squared. Square area = side squared. Tin ratio = new tin area / original tin area.

About this calculator

The Cake Tin Size Converter compares tin areas so you can adapt a cake recipe from one round or square tin to another. It helps bakers avoid batter that is too shallow, too deep, underbaked, or overflowing.

Cake Tin Size Converter method

The calculator applies the visible formula to the values entered. It is designed for practical planning and checking, so keep the assumptions visible when comparing scenarios.

round tin area = pi x radius x radius
square tin area = side x side
scale factor = new tin area / original tin area

How to use the Cake Tin Size Converter

Choose the original tin shape and enter its size.
Choose the new tin shape and enter its size.
Compare the tin areas.
Use the scale factor to adjust ingredients if needed.
Consider batter depth as well as surface area.
Adjust baking time and check doneness early.

Worked examples

20 cm round to 23 cm round

Input: Original 20 cm round tin, new 23 cm round tin

Calculation: new area / original area is about 1.32

Result: Scale ingredients by about 1.32 for a similar depth.

Round to square tin

Input: 20 cm round cake into 18 cm square tin

Calculation: compare round area with square area

Result: Use the factor to decide whether the square tin needs more or less batter.

When this calculator is useful

Use it as a quick planning tool before editing a recipe, placing an order, choosing packaging, or comparing options. For anything that affects safety, delivery terms, customer pricing, or a commercial commitment, check the final details against the original recipe, supplier, courier, or official source.

Inputs that matter most

Tin area: Area is the main driver for a similar cake depth when the recipe style stays the same.
Tin depth: A shallow sandwich tin and a deep cake tin can behave differently even if the top area is similar.
Batter type: Dense fruit cake, sponge, brownie, and cheesecake batters do not all respond the same way.
Lining and headroom: Leave space for rise, especially with sponge and loaf-style cakes.

Common mistakes to avoid

Check 1: Do not fill a tin to the top; many cakes need room to rise.
Check 2: A deeper cake may need a lower temperature or longer bake.
Check 3: Square corners can bake faster than the centre.
Check 4: Loose-bottomed tins can leak thin batters unless lined well.

Planning notes

Area	What to check
Units	Keep grams, millilitres, centimetres, kilograms, and time units consistent.
Rounding	Round practical kitchen or shipping values after checking the calculated result.
Tolerance	Allow margin for packaging, recipe texture, oven variation, courier rules, or handling space.

Edge cases

Do not fill a tin to the top; many cakes need room to rise.
A deeper cake may need a lower temperature or longer bake.
Square corners can bake faster than the centre.
Loose-bottomed tins can leak thin batters unless lined well.

Limitations

This is a practical baking estimate. Oven performance, tin material, batter type, and recipe method can change the final result.

The calculator compares tin surface area, not exact heat transfer or batter chemistry.
Always test doneness with the method recommended by the recipe.

Frequently asked questions

Is a 20 cm round tin the same as an 8 inch tin?

They are close but not identical. An 8 inch tin is about 20.3 cm.

Can I use a square tin instead of round?

Yes if you compare areas and keep batter depth sensible.

Do I change oven temperature?

Usually keep the recipe temperature unless the cake becomes much deeper or shallower.

Why did my cake sink after scaling?

It may be underbaked, overmixed, overfilled, or affected by raising agent changes.

Can this scale brownies?

Yes. Brownies often tolerate pan changes well, but thickness changes texture and baking time.

Related calculators

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What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.