Different IBU numbers for same recipe

[Gerry P]

I just posted a recipe for an Arrogant Bastard clone. The recipe calculator lists the IBUs as 90, but the recipe search lists it at 83. Anyone know why they're different?

 

[Ozarks Mountain Brewery]

ibu's are not exact, and they are always different in different software, we can only get close with our system and know how bitter it is to us as a recipe builder, in other words you will never match someone else's system perfectly

also ibu's will taste different for every water source, the minerals, hardness or softness of the water greatly changes the perception of ibu's in home brew

 

[Gerry P]

Yep I hear ya, that's to be expected sometimes. But what I'm saying is there are 2 different IBU numbers for the same recipe here on Brewer's Friend. When you pull up my recipe it says 90 IBUs, but if you do a search for "Arrogant Bastard" and find mine on the list (it's the 2.5 gallon batch size), it says 83 IBUs. I know it's not a huge difference, I'm just thinking that might need fixing.

 

[Gerry P]

OK never mind. My recipe is going by Tinseth, the search results are using Rager. My bad, thanks for the reply.

 

[Ozarks Mountain Brewery]

no problem, I just remembered another thing that can seem wrong but isn't, when they have made drastic changes to the system and an old recipe doesn't get re-saved after the changes but a new one does, the stats can seam wrong.

one thing that comes to mind "not related" in that area is the final gravity changing based on mash temperature and yeast high and low tolerances. they've made changes to both and an old recipe could say 15 final gravity but re-saved and it would drop to 12

there may be other changes that might seem wrong to the recipe !!

 

[Gerry P]

I don't think anything was wrong, it just switched up the method of calculating IBUs on me. Either one was "correct", according to whichever one you prefer.