Traybake and Tin Size Converter
Enter the tin the recipe asks for and the tin you actually have.
Optional. Helps us warn you if the batter would come too close to the top.
Answer
Multiply everything by 1.7
The numbers
Watch the depth
Your new tin is much bigger. If you keep the recipe the same, the bake will be shallow and will cook faster. Scale the recipe up instead.
Next step
Worth knowing
- Tins are compared by the area of their base, not by their width. A 23cm round tin holds about a third more than a 20cm one.
- Multiply every ingredient by 1.7 to keep the same depth of bake.
- Baking times change less than quantities do. Start checking at the original time and use a skewer.
Source: Standard UK tin sizes and batter/filling quantities used in home baking · Reviewed 2026-09-10 · Guidance version 1.0.0
Reference and detail
Area is what counts
Swapping a 20cm round for a 23cm square is a bigger jump than it looks, because you are comparing surface areas rather than measurements. The multiplier here does that for you.
Keep the temperature, change the time
A thinner bake in a larger tin cooks faster; a deeper one takes longer. Leave the oven where the recipe says and start checking earlier or later as suggested.
Watch the depth
If the scaled batter would come more than two thirds up the tin, split it between two tins. Overflowing traybakes are difficult to rescue.
Questions and answers
Questions about converting traybake tin sizes
How do I scale a traybake recipe to a different sized tin?
Enter the tin the recipe was written for and the tin you actually own above. The calculator compares their base areas and gives you a single multiplier to apply to every ingredient.
Will a traybake in a bigger tin need a shorter baking time?
Usually yes. The same amount of mixture spread into a larger tin makes a thinner bake, which cooks faster, so keep the oven temperature as written and start checking earlier than the recipe suggests.
A smaller tin has the opposite effect, a deeper bake that takes longer and may need covering with foil if the top browns before the middle sets.
What if the scaled mixture won't fit in my tin?
If the multiplier above would take the mixture more than about two-thirds up the sides, split it between two tins rather than overfilling one. An overflowing traybake is very hard to rescue once it's in the oven.
Does swapping a round tin for a square or rectangular one change the amount I need?
Yes. Shape changes the area even when the width looks similar, so always convert by entering both tins rather than assuming a 'similar sized' tin is a like-for-like swap.
Guidance
Read the full guide
- Cake Tin Sizes and Recipe ScalingHow to bake a recipe in the tin you actually own: matching area rather than width, adjusting batter quantity, and what happens to the baking time.