WTK: Proper IBU Range for Imperial Porter

I plan on brewing an imperial porter (derived from an incomplete recipe) with a starting gravity of 1.086 to 1.088 that should terminate around 1.016 to 1.018 for an ABV of 9%.

The recipe calls for Phoenix @ 90 minutes and First Gold @ 30 minutes.

What I don't know is the IBU target of the recipe.

So ... with an imperial porter starting at 1.088, what should the IBU target be?

I would shoot for around 40 IBUs

I have an imperial porter coming up and I've been wondering the same thing. The target gravity is about the same too, but I'm going for 55 IBUs. I may keep it at that or up it a little bit, considering that I'll be using a low attenuating yeast (Scottish Ale)

Instead of looking at the IBU's, look at the BU:GU ratio. That is a more accurate way of looking at it.

Here is a good link. They don't have Imperial Porter in there but Robust Porter is there.

http://www.madalchemist.com/chart_bitterness_ratio.html

Do you plan on aging the beer? If so you might want to bump up whatever your target bitterness level is because some will be lost during that process in my experience.

OK, so the BU:GU for a Robust Port is .66 - help me put that into a real world measurement.

The ratio is bitterness units to gravity units. So your OG is 1.088, so 88 IBUs would be a ratio of 1. Multiply 88 by .66 (desired BU/GU ratio) and you get 58 IBUs.

I've made Imperial Stouts in the 55-60 IBU range and that gravity and it worked well. If you want a smoother, slightly sweeter beer, target 40-50 IBUs. The difference between an "Imperial Porter" and an "Imperial Stout" is just semantics IMO, but I would expect the Porter to be a bit less roasty, a bit sweeter and a bit less bitter in direct comparison to anything called an Imperial Stout.

That said, Southern Tier's Creme Brulee Imperial "Stout" is not at all bitter and exceedingly sweet, so it really just comes down to your tastes, your goals for the brew, and what you want to call it.

There really isn't a right answer...but under 30 IBU would likely not be nearly enough to balance the malt and 70 would be too much!

I'll keep researching and analyzing existing recipes. I agree, 30 seems a bit less while 70 is over the top.