Before we get to the part where we discuss light and brown sugar, you should know what divides plain white sugar from brown sugar.

Basically, white sugar is crystals taken from sugar beets or sugar cane. When white sugar is refined, all moisture is stripped away and molasses is left behind.

To make brown sugar, molasses is either left in the sugar crystals or added later on.

Now, what is the difference between light brown and dark brown sugar?

It all comes down to one thing: how much molasses each one has. Light brown sugar has about 3.5% molasses and dark brown sugar usually has around 6.5%. The higher percentage of molasses makes dark brown sugar a little bit more moist and acidic and it will have a stronger flavor.

If you’re in a pinch when you’re cooking or baking, you can replace one for the other but it might have a little effect on your final product.