Ibu's

[GSRman]

I'm going to be brewing later this week, and i was wondering how the hell to calculate IBU's (i extract brew) anyone know of a good website on it?

can anyone explain it in terms i can understand?

 

[jayse]

the formula is

ibu x litres x 10 / a.a% x efficency(32 for 1 hour .24 for half hour)



so 25 ibu of cascade at 5.7% in a half hour boil for 23litres is

25ibu x 23litres x 10
-------------------------- = 42 grams
5.7 a.a% x 24

 

[Wasabi]

Jayse,

Thanks for that, for some reason it looks so much easier to read than Palmers calc, but perhaps it's being in Metric that helps.

 

[GSRman]

how does having a smaller boil affect the efficiency, eg i only boil around 12L..

what about the 15 min and 10 min type efficiencies?

 

[jayse]

GSRman
the smaller boil is allright but its the gravity of the wort your boiling that really matters it should be under 1.050 for the efficency i gave above.so if your extract brewing with a small boil it proberly would be best not to boil all the extract.

for the 15 -10 mins additions i normally don't even worry about calculating them.but to do it use

19 mins - 19
15 mins - 15
10 mins - 10
5 mins - 5
0 mins - o

 

[GSRman]

cheers.......

 

[Jethro]

I have found this website" http://brewery.org/ ", handy for designing my brews It gives approximate IBU alcohol and colour and compares to the beer style you are trying to achieve. Just go to the recipe calculator.( I also use the calculations on an Exel spreadsheet but I cant work out how to post this). Here is a copy of one recipe Idesigned with the calculator (fun and easy)

24th.May 2003 Seaton Cascades
Just copied a recipe from a bloke at work
Brewer: J.F.Martin Email: -
Beer: Seaton Cascades Style: English Pale Ale
Type: Extract w/grain Size: 22 liters
Color: 12 HCU (~8 SRM)
Bitterness: 27 IBU
OG: 1.047 FG: 1.012
Alcohol: 4.5% v/v (3.5% w/w)
Grain: 200g British crystal 50-60L
Steep: Cracked and boiled th cristal malt in 2 litres of water
Boil: 60 minutes SG 1.047 22 liters
3kg Light malt extract200g Light dry malt extract
200 gms DME 1/2 KG LIGHT MALT EXTRACT FOR first 50 minutes then add the last of the Malt
Hops: 30g Cascade (8.3% AA, 60 min.)30g Cascade (aroma)
Yeast: Safale
Log: Brewed 24th May 2003 Fermented at 18 C for 1 week Bottled on 31st May 2003
Carbonation: Bulk Primed with 180 grams DME