The previous version outlined the minimum capacity requirements necessary deploying Exchange databases and transaction logs. It did not account for the fact that customers may not want to design a LUN at maximum capacity or miss the fact that they were designing the LUN at maximum capacity. Therefore, we added a new parameter called "LUN Free Space Percentage" which adds additional space into the disk space calculations to ensure there is head room for each LUN.
We have attached the new version of the calculator to the original post. Let us know if any questions/suggestions!