Substituting Fermentables - how much is too much

I’d like to replace some of my malt bill with sugar - a la Belgian style, for the purpose of maintaining ABV, while sort of thinning out the final body of the beer. Trying to make it less “chewy” in the bottle, more light-bodied like a Trippel.
How much is too much to add? My malt bill is 12-13 lbs base malt, plus some cara and roasty, I think taking out 2 lbs malt and sub-ing 2 lbs sugar? But it doesn’t sub pound for pound, does it?
And is corn sugar alright, or candi sugar better? I’ve added corn sugar and honey in the past, but never more than a pound per batch.
Any thoughts?


I think sugar is 1.042 or 1.044 points per pound per gallon, as opposed to 1.035-1.038 for base malts. and it’s 100 % reliable (no extraction efficiency to think about), so in practice the difference might be a little greater.

I’ve gone up to 10% in a tripel and Denny says his is 80% pils, 20% sugar.

Table sugar is just fine. The Belgian dark syrups are worth it for flavor, but if you’re just boosting alcohol, you don’t need the extra expense.

Stan Hieronymus has a great overview of sugar used in Belgium