I have been looking at the values stored in the Inventory and the associated HSI (Hop Storage Index) - most of which seem to be zero (or missing?) and wondered what this was all about. From what I have gathered - and there is not much information on here - the HSI is an adjustment value applied to the AA value of a hop that depends on how it is stored after harvesting and how long for at a specific temperature. There is no calculator for that on here - that I have found - so I decided to work one out in Excel and compare that with the facilities found in Beersmith and HomeBrewMap sites. The calculation shown below follows - fairly closely - those found on the other sites so perhaps it could be included on here - assuming of course if anyone was interested to use it. In the final line of the equation below: STy = Storage Type, Sti = Storage Time I used the values of AA published on this site as part of the Excel spread sheet calculator with Validation values set in the appropriate cells in column B and the calculator was only worked in degrees C so if you use the maths shown here for US temperatures in Farenheit you will need to build that conversion in. As an aside to this why are only a few Hop values on here got the HSI value set? Is it because they don't matter or is it because no one has worked them out yet? Does the Recipe Calculator for IBU take the HSI value into account?