Starting my first batch in a couple weeks

Picked an extract/steeped grains brew to start. The recipe I picked was the All Amarillo IPA, found on this site. I say picked, not following, as I pretty much had to substitute every ingredient. Here's what I devised (5 gallon batch):

7 lbs Pale DME
0.5 lbs Carastan 30-37L
1.5 oz. Centennial 8% @ 60
1 oz. Centennial 8% @ 15
1 oz. Centennial 8% @ 5
0.5 oz. Centennial 8% @ flameout
Safale US-05 dry yeast

One particular issue is cropping up when I run the recipe through various brewing software; while they all tend to agree (pretty closely anyway) on ABV, OG, and FG, I am getting major league variations on the IBUs. BeerSmith puts it around 45 BU with a 4 gal. boil, QBrew pegs it at 61 IBU (no ability to set boil vol.), and TastyBrew puts it at 84! IBU with a 4 gal. boil. So who is right??? From what I gather looking at other recipes, this is a pretty light hop bill for an IPA, so I'm leaning towards the BeerSmith calculations as being correct, but was hoping the kind folks here might have some better in-sight.

I'm also curious about how much yeast to use; will one 11.5 g package be enough? I have two on the way, but don't want to waste it if I don't have to.

Any help would be greatly appreciated. Awesome site!

I would go with beer smith. Besides the programs are just what stats are supposed to turn out if everything goes as planned. I would just worry about OG and TG.

I pretty much always use 1 packet of dry yeast. There are a bunch of yeast cell in that packet should be fine for 5 gallons.

Thats gonne be yummy.mmmm centenial hops.

I wrote my own calculator because it gives me complete control over how the calculations are performed. It uses the Tinseth formula, which usually comes out between Rager and Garetz.
Assuming that you add all the DME at the start of the boil, that you boil from 4g down to 3.25, and that you top up to exactly 5g, Tinseth forecasts 41 IBU
If you add 1.5# DME at the start of the boil, and 5.5# at the end, but keep everything else the same, the forecast would change to 78 IBU
If you can give me the pre-boil volume, the post boil volume, the boil time, the extract addition amounts and times, and your final volume (after topping up), then I can rerun the numbers to give a more accurate estimate.

-a.

P.S. Add 10% to those values if you are using pellet hops.

Thanks all for the replies. Joos, I hope you're right!

ajf,

Thanks for the info. I hadn't thought about a late extract addition to up the IBU. The less dense wort allows better hop utilization, correct? If so, this might be exactly what I should try.

Thanks also for the offer to run some numbers for me. I can give you pre-boil, boil time, and final volume, but I would be guessing at the post-boil, as I have no clue about determining an evaporation rate. Would 7-8% be a safe guess? If so, should look something like this:

Pre-boil: 4 gal (3.5 in pot, plus 0.5 steeping and sparge water)
Post-boil: 3.5 gal
Boil time: 60 min
Final vol: 5 gal

Taking the above into account, how would I split the DME to get an IBU level of around 55-60?

Thanks again. Really appreciate the help. Cheers

I just ran a few variations through Beer Smith, and came up with the this:

Boil volume: 4 gal
Boil-off volume: 3.53 gal
Final volume: 5 gal
4 lbs Pale DME (60 mins)
3 lbs Pale DME @ 10 mins
0.5 lbs Carastan (steeped, added at start of boil)
Hop schedule stays the same

Here's what it spit out at me:

OG 1.062
FG 1.016
IBU 60.9
ABV 5.97%

Sound like I'm on the right track?

Sounds close, but I question Beer Smiths gravity calculation.
DME yields 46 pppg, so 7 lbs DME yields 7 * 46 / 5 points in 5g = 1.064
The Carastan would yield another 1 - 2 points, so your OG should be at least 1.065.
I would suspect that Beersmith is losing you 3 points because you don't transfer all the wort to the primary. My calculator doesn't take this into account.
I don't know if you have Beer Smith set up for Tinseth (which is what I'm using), and that could account for a few IBU's. Also, going down to 3.53g instead of 3.50 would make a difference of about 7 IBU's
I calculated that 5 lbs DME at 60 minutes and 2 lbs at 10 minutes would result in 59 IBU's using your original hop schedule, and boiling down to 3.50g.

What was more interesting, is that using 2 lbs DME at 60 minutes, and 5 lbs at 10 minutes, you could cut the 60 minutes hop addition down to 1 oz instead of 1.5, and only lose about 5 IBU's. I suspect that Beer Smith would show something very similar.

Be aware that these are only predictions, and they will not be 100% correct, and that you won't be able to taste the difference between a few IBU's

Good luck.

-a.