Scalling a recipe to reduce the gravity - hops

[dreaddan]

Hi, I've got a recipe I crated at 9% but I want to create a lower grav version.
Brewfather allows me to scale the grain easily but doesn't scale the hops.

I'm not sure what is the best way to change them - do I adjust them the same amount as the grain or something else?

 

[Baldylocks Brewery]

Hi Dreaddan if you want a lower Abv but it’s the same batch size wouldn’t the hop additions stay as is or the IBU, hop taste and aroma will be lower?
Unless that needs toning down as well?

 

[dreaddan]

Some will need to change if not all to get the right bitterness and taste.

The original recipie has a ibu of 55 which gives me a bu/gu 0.61 which is bang on the middle of the jazy/jucy impetal/double ipa profile.
If I swap that to the same profile but for a standard ipa and scale the recipe to 6.2% the ibu goes to 69 with a bu/gu of 1.11.

What I don't know, if if I just adjust the bittering hops or everything?

 

[Sadfield]

You most likely want to scale back to bittering addition so the relationship between bitterness and malt sweetness is the same. Have a look in Brewfather it should give a (Relative Bitterness Ratio) BU:GU value.

Late hops can stay the same or be reduced, that's a judgement call based on the style being brewed. Fir a stout you may want to dial it back, but then not for an IPA.

Same, but perhaps less so for dry hopping.

A good way to approach it is to adjust the late hops as required, then adjust the bittering addition to match the BU:GU value to the initial recipe.