Calculating IBUs (all extract)

[pursuit0fhoppiness]

Hi guys, I'm currently fermenting my first batch but during my brew day I was a little confused on calculating how many IBUs I'd end up with. I boiled for an hour (added 4 of my 6 pounds of DME, then added last 2 with 5 mins left to pasteurize), and added 1 oz of 14.9% AA Columbus hop pellets at 45 mins and 1 oz at 15 mins. The part I'm confused with in the equation is the boil gravity. When should I have taken that reading? As soon as DME is all dissolved at start of boil before hop addition? After hop addition? OG once boil is finished?

Thanks for your help all

 

[pursuit0fhoppiness]

Oh forgot to note I also steeped 1 lb. of 10L caramel malt for 30 mins before starting boil.

 

[BeerAddikt]

I'd recommend using Beer Smith (http://beersmith.com/) or Brewers Friend which I prefer (https://www.brewersfriend.com/), input your recipes and let their calculators do the work. Unless you are the type of person who likes to geek out on math this is the route most of us go.

Both of these will also estimate many other things for you such as gravity, SRM and a host of other useful tidbits.

But to directly answer your question you would calculate with the gravity at the point of the hop additions. The 2 lbs DME added with 5 min left will have minimal impact on your IBUs so just disregard. IBUs is always just an estimate anyway.

 

[pursuit0fhoppiness]

Thanks BeerAddikt, I like that you can input target OG to brewersfriend and it'll estimate your boil gravity for you. Since I'm calculating after the fact and know my actual OG, it's likely a little more accurate. Looks like my APA will be about 60 IBU! (A little higher than the BJCP guidelines.. but hey it's my first batch)

 

[deks77]

Looks like my APA will be about 60 IBU! (A little higher than the BJCP guidelines.. but hey it's my first batch)

I run a little higher using beer smith, just preference. Just did my first competition and the one that was within guidelines came back low hop aroma.. the one that was over made a second place ( i give credit to all the reading ive done here) .. so it's kinda judgment call. I dont fault the programs cause we all brew a bit different. Just have to find wht works for you.

 

[eric19312]

Thanks BeerAddikt, I like that you can input target OG to brewersfriend and it'll estimate your boil gravity for you. Since I'm calculating after the fact and know my actual OG, it's likely a little more accurate. Looks like my APA will be about 60 IBU! (A little higher than the BJCP guidelines.. but hey it's my first batch)

My favorite APA recipe comes in at 55 IBU and about 6%. It does well in competitions last time got a 41.

 

[Silver_Is_Money]

No matter how hard you try to pinpoint IBU's in advance, you will only be able to land your actual IBU's at somewhere within roughly +/- 25-30% of your desired initial target. And there is seemingly more likelihood to come in low to midland vs. high.

Calculating IBU's for extract batches should be no different than calculating the same for all grain batches.

 

[BeerAddikt]

Thanks BeerAddikt, I like that you can input target OG to brewersfriend and it'll estimate your boil gravity for you. Since I'm calculating after the fact and know my actual OG, it's likely a little more accurate. Looks like my APA will be about 60 IBU! (A little higher than the BJCP guidelines.. but hey it's my first batch)

60 IBUs in a pale will be lovely. Once you go all grain brewersfriend is even more amazing. It does water calculations and mash schedules, including the sparge, so you don't have to try to figure them out yourself. As with all things, you will need to adjust for your brew house setup but once you've done a few batches you will know exactly what to do once you've input your recipe. The only thing I don't use in brewersfriend is the water profile tool. Bru'n water works much better.

 

[ncbrewer]

As has been stated, IBU calculations are not real accurate, due to many variables. But John Palmer and others have recommended picking one of the traditional formulas for all your batches, and you will have consistency. (Until you change your process.)