Calculate IBU's

[alaskantuff]

Having trouble figuring out which method to use when calculating my ibus....there seems to a million different ways to figure it and with each method i come out with a very different answer than the last. I want to use the most common calculation, the one most US breweries use. Can anyone tell me the formula for that? And what its called.

 

[Sailingeric]

You could cheat and use Brewers Friend or similar site to see what you get. http://www.brewersfriend.com/ibu-calculator/

 

[alaskantuff]

You could cheat and use Brewers Friend or similar site to see what you get. http://www.brewersfriend.com/ibu-calculator/

Yea, I have the app on my tablet but I kinda want to know the formula so that I can do it on paper, can't rely on technology too much.

 

[hannibalmdq]

Yea, I have the app on my tablet but I kinda want to know the formula so that I can do it on paper, can't rely on technology too much.

I stripped out some stuff from my brew day google docs project. Here's a simple implementation for Tinseth IBU for additions during the boil. It's taken from the equations on Tinseth's site (http://www.realbeer.com/hops/).

I should add there are additional tweaks other have done, including adjusting the gravity/volume components of the equations according the what the gravity is at the time of the addition. People go back and forth and what they think is the most accurate. My take on it is that this is all just an estimate, and as long as you as estimating consistently you can let your tastebuds do the rest. The only real way to determine IBUs is to ship a sample off the lab. Just use one formula and figure out what 20,30,40,120 IBUs tastes like to you, and then use it to plan your recipes.

IBUs are only one component of hops anyway. There's a lot of other flavors and smells that aren't captured by the IBU number.

function hopUtilization( HopTime,OriginalGravity,HopType) {
    var isPellet = HopType=="Pellet";
    var utilization = (1.65*Math.pow(0.000125,(OriginalGravity-1))*((1-Math.exp(-0.04*HopTime))/4.14));
    utilization = isPellet?utilization*1.1:utilization;
    return utilization;
}


function calcIBU( Utilization, HopWeight, HopAlphaAcid, PostBoilVolume){
     return (Utilization*(HopWeight*HopAlphaAcid*7490)/PostBoilVolume);
}

 

[Oginme]

Having trouble figuring out which method to use when calculating my ibus....there seems to a million different ways to figure it and with each method i come out with a very different answer than the last. I want to use the most common calculation, the one most US breweries use. Can anyone tell me the formula for that? And what its called.

There are a number of formulas for calculating IBUs. All are based upon someone's experimentation and measurements and all are only really correct with the given system that they were developed on. Everyone has a different process and utilization rate of the hop acids.

Assuming like the rest of us that you are not going to be sending out your beer for testing, I would recommend the following:

1) Pick one of the equations (Garetz, Tinseth, Rager) and stick with it. I think the most popular two are the Rager and Tinseth models.

2) Select a couple of commercial beers with published IBU levels and get a couple of bottles.

3) Brew similar styles of beer with the bitterness approximately equal to the levels of the commercial products you chose, using the model you chose.

4) When finished, taste and compare the bitterness of the similar commercial product. Are you more bitter or less? This will guide you on how to manage your recipe design to achieve the bitterness levels you want.

 

[alaskantuff]

Thanks guys I guess I'll just stick to what I've been doing then. Appreciate your time.