Home of the BrewNosers

Morning everyone!

If I am working on a recipe and I increase my grain percentage by, say, 5% to achieve a target ABV, should increase my hop quantities by the same 5% or is it more complicated than that?

Thanks in advance!

It's more a little more complicated than that. Are you using software? If not I suggest you use it. Do you have a certain BU:GU ratio you are shooting for?

When you say adjust the grain to reach a target ABV, do you mean to adjust for your individual mash efficiency so that you can hit the target in the recipe? If so, then you don't need to adjust the hops at all. The hop level in a recipe is set relative to an expected gravity level. It doesn't matter how much grain you need to run through your system to get there, but rather what the gravity going into and out of your kettle is.

If you mean you want to bump up the ABV from what's in the recipe, then you've got to alter your IBUs to compensate for the increased residual sweetness. In your hypothetical example, 5% is within the margin of error/taste threshold, and I don't think I'd bother doing anything. For larger changes, its almost a relative increase, with the caveat that increased gravity leads to decreased hop utilization, so the amount of hops needs to increase slightly more than the amount of grain. To the best of my knowledge, there's no effect on extraction of flavour and aromatic compounds with increased gravity, so if you're just tweaking ABV a touch, and not changing style, you can probably leave your late additions alone (unless you're getting a substantial portion of your bittering from giant whirlpool additions or something).