Welcome to the Cake Decorators Q&A

I have a sponge cake recipe with 125g of soft brown sugar…… can I substitute caster sugar instead and will I need to change the amount used?

Thanks for your help

CakeFlix Guidance

Yes, you can use soft brown sugar instead of caster sugar in many everyday cake recipes, usually replacing it with the same weight. However, the finished cake may have a different flavour, colour and texture. Light soft brown sugar is generally the closer option when you want a milder change.

Run out of caster sugar halfway through preparing a cake? Before reaching for another packet, consider whether a little caramel flavour would suit your bake.

Can I use light brown sugar instead of caster sugar?

Light soft brown sugar often works well in straightforward sponge cakes, banana cakes and other everyday bakes. If the recipe calls for 125g caster sugar, try 125g light soft brown sugar.

Madeitwithlove reports successfully swapping these sugars without changing the quantities. That is a useful starting point, although it won’t give identical results in every recipe.

Brown sugar contains molasses, which contributes flavour, colour and moisture. Your cake may be darker, with a slightly different crumb. Dark soft brown sugar gives a stronger flavour, so choose light brown when you want a less noticeable change.

Can I use caster sugar instead of brown sugar?

You can often make the reverse swap in a simple cake, using the same weight. For the original question on this page, 125g caster sugar can replace 125g soft brown sugar, with some changes to the result.

Expect a lighter colour and less caramel flavour. The texture may change too, particularly in recipes that rely on brown sugar for moisture or chewiness. For more alternatives, see King Arthur Baking’s guide to brown sugar substitutes.

Are all brown sugars interchangeable?

Soft brown sugar is not the same as coarse demerara sugar. Larger crystals can behave differently during mixing, while muscovado has a more pronounced molasses flavour.

Also, soft brown sugar is not always unrefined: some products are made by adding molasses to refined white sugar.

When should you follow the recipe exactly?

For delicate whisked sponges, meringues or a cake where a pale, light finish matters, stick with the specified sugar. A successful substitution in one recipe doesn’t guarantee the same outcome in another.

Weigh your sugar, break up any lumps and note how the finished cake turns out. Explore our golden caster sugar guide and baking tutorials for more ingredient advice and recipes.

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Hi jen2014

I very often do subsitute the two sugars without any problems. It’s just all sugar with a similar texture however soft brown sugar is unrefined and feels stickier and tastes tangier. I never change the quantites and all works out fine.

Many thanks for your reply and for putting my mind at rest…..