Reposted from the brewing discussion forum since there may be an issue in the Beersmith yeast calculation that needs to be investigated.

Using the Yeast Starter Tool for a 5.25 Gallon batch with an OG of 1.067 both BS2 and MrMalty calculate ~242 Billion Cells.

Using Liquid Yeast packaged on 11/6/2011 both tools estimate ~67% Viability.

Now when you get to the calculation for the size of the starter in BS2 without a stirplate the internal calculation of the number of packs needed without a starter appears to be incorrect. With the above inputs BS2 suggests that 6 yeast packs are needed which it 2 times as much as is really needed

6 packs x 67 Billion cells / Pack = 402 Billion cells

The ideal pitching rate is 242 Billion cells.

The calculation then suggests that 2 vials in a 3.09 Liter starter is required which is about 1 L more than necessary to achieve a 1.86 growth factor.

Would you take a look at the internal calculations in BS2? If there is a conversion factor error or an incorrect table lookup that could impact the calculation of the starter size needed with a Stir Plate.

Cheers