Gravity calculations

General discussion on BeerTools Pro Software.
Post Reply
HerrUU
Posts: 3
Joined: Thu Jan 29, 2015 1:49 am

Gravity calculations

Post by HerrUU » Thu Jan 29, 2015 2:01 am

Hi,

Since last week I am the proud owner of a BeerTools license :D Let me start by saying that I like the tool a lot. Good layout and intuitive design.

But I have a question. How is the gravity calculated per fermentable? Which parameters are being used from the fermentable spec sheet? The reason I ask this is twofold.
In comparison to other calculators (for instance Beersmith or BrewTarget), it seems that Beertools gives a lower gravity when entering the same parameters in all softwares. I'm sure that the calculations behind are sound, but I would like to understand them.
Secondly, I'm from Belgium and I have access to a range of malts that are not present in the tool (Brewferm malts). I would like to enter them manually but am a bit confused whith the terminology in the input sheet for a new fermentable.

Thanks for your help,

Walter

ps : Please forgive me if by some chance I made some mistakes in writing this post but English is not my native language :wink:

User avatar
jeff
Imperial Stout
Imperial Stout
Posts: 1508
Joined: Sun Jan 09, 2000 8:16 pm
Location: Hollywood, SC
Contact:

Re: Gravity calculations

Post by jeff » Thu Jan 29, 2015 9:23 am

Hi Walter. Thanks for choosing BeerTools Pro!

Let’s go through an example of how to add a pale malt to the database, and see how gravity is calculated from this grain.

To start, we need to know the laboratory extract and enter it in the DBFG (dry-basis fine grind) field. In this case it is 80.0%. We also need to know the FG-CG (fine-coarse difference) which is 1.5% for this grain. This gives us 78.5% for our DBCG (dry-basis coarse grind).

The next critical value is moisture. Since moisture affects the weight, the higher the moisture, the lower the yield. A typical moisture is 4.0% so we will use that here. That brings us to the AICG (as-is coarse grind) value which deducts 4.0% of our DBCG leaving us with 75.4%.

The first step to calculating gravity is to determine the grain’s potential by finding the product of AICG and the constant 46.214. In this case we get 34.8. Dividing 34.8 by 1,000 and adding 1 results in 1.0348 potential gravity. That’s the gravity we can expect from one pound of grain in one gallon if our brewing system is 100% efficient.

Since our brewing system is not likely 100% efficient we can expect less than 1.0348 from our grain. For example, if our efficiency is 80.0% we can expect 1.0279 from one pound of our pale malt in one gallon.

So, when adding your grains, the most important values that must be entered are DBFG, FG-CG and moisture. For color estimations, the color should be entered too.

I hope this clears things up.
Jeff
BeerTools.com Staff

HerrUU
Posts: 3
Joined: Thu Jan 29, 2015 1:49 am

Re: Gravity calculations

Post by HerrUU » Thu Jan 29, 2015 9:50 am

Thank you, Jeff, it was exactly what I was looking for.

It's a really accurate way to calculate gravity. Now I can enter the new malts into BeerTools and start brewing :D

User avatar
jeff
Imperial Stout
Imperial Stout
Posts: 1508
Joined: Sun Jan 09, 2000 8:16 pm
Location: Hollywood, SC
Contact:

Re: Gravity calculations

Post by jeff » Thu Jan 29, 2015 10:22 am

Please let me know if you have current specifications for Brewferm malts. I can use the data to add them to the permanent database distributed with BeerTools Pro and the ingredients available on BeerTools.com.
Jeff
BeerTools.com Staff

funkmaster3000
Posts: 1
Joined: Wed Apr 19, 2017 12:35 pm

Re: Gravity calculations

Post by funkmaster3000 » Wed Apr 19, 2017 12:43 pm

Hello,

I'd like to ask a follow up question. How the terminal gravity is calculated without any yeast added to the recipie? As the strains differ in attenuation, surely this parameter should differ. When using different recipie software the terminal gravity wasn't calculated prior to adding yeast.

Thank you.

Post Reply