### Author Topic: Tinseth Hop Calculation Help  (Read 3958 times)

#### NorthernIke ##### Tinseth Hop Calculation Help
« on: January 16, 2010, 07:50:56 PM »
I'm sick of looking up hop utilization numbers when building recipies.  I use a spreadsheet that I built for my brewing "software".

I need some help building an equation in Excel.  I use the Tinseth formula, and on his page on of the stated factors is "boil time factor".  This is determined by this equation:

The Boil Time factor accounts for the change in utilization due to boil time:

Boil Time factor = 1 - e^(-0.04 * time in mins)
--------------------------
4.15

My question is what does "e" refer to in the above equation?  How do I program this into Excel?

Here is Tinseth's page where I got the formula:  http://realbeer.com/hops/research.html

Thanks!

#### NorthernIke ##### Re: Tinseth Hop Calculation Help
« Reply #1 on: January 16, 2010, 07:54:16 PM »
From Wikipedia: http://en.wikipedia.org/wiki/E_%28mathematical_constant%29

The mathematical constant e is the unique real number such that the value of the derivative (slope of the tangent line) of the function f(x) = ex at the point x = 0 is exactly 1. The function ex so defined is called the exponential function, and its inverse is the natural logarithm, or logarithm to base e. The number e is also commonly defined as the base of the natural logarithm (using an integral to define the latter), as the limit of a certain sequence, or as the sum of a certain series (see the alternative characterizations, below).

e is one of the most important numbers in mathematics, alongside the additive and multiplicative identities 0 and 1, the constant π, and the imaginary unit i. (These are the five constants appearing in one formulation of Euler's identity.)

I guess I'm no Mathlete!  I'm going to try and plug this into Excel...maybe it's smarter than me...

#### NorthernIke ##### Re: Tinseth Hop Calculation Help
« Reply #2 on: January 16, 2010, 08:12:42 PM »
Thanks to Wikipedia..."e" can be described as:

2.71828182845904523536

This seems to make the Excel formula work like a champ!  Maybe this will come in handy for someone, someday...but probably not!

#### a10t2 ##### Re: Tinseth Hop Calculation Help
« Reply #3 on: January 16, 2010, 08:28:37 PM »
You can also enter it exactly (or at least, to a whole lotta digits - I don't know if Excel uses a stored value or not) by using the exp() function.
Sent from my Microsoft Bob

Beer is like porn. You can buy it, but it's more fun to make your own.
Refractometer Calculator | Batch Sparging Calculator | Two Mile Brewing Co.

#### hopfenundmalz

• Global Moderator
• I must live here
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• Milford, MI ##### Re: Tinseth Hop Calculation Help
« Reply #4 on: January 19, 2010, 12:33:42 AM »
Remember that your input data will be 2 sig. figures.

Don't quote your output IBU's to 12 decimal places. Jeff Rankert
#### skiwithg 