[repo]

I think people get too caught up in yeast cell count. To me, if you have a 2L starter it does not matter how many cells you started off with you still have a 2L starter (as long as the yeast has finished). My guess is if you had a flask with a pack that was 75% viable and another flask with a pack that was 25% viable they will end up with approximately the same cell count. The 25% viable pack will just take a little longer. So why bother trying to figure out how many cells you have. Just figure out how many mL of starter you need for a given brew...

Really Wow I just don't know where to begin trying to help you. I'll just say your guess would be way off. Oh and the size of your starter is only relevant to the number of  viable cells you have. That's how you determine the size starter you need. 

[roguejim]

I think people get too caught up in yeast cell count. To me, if you have a 2L starter it does not matter how many cells you started off with you still have a 2L starter (as long as the yeast has finished). My guess is if you had a flask with a pack that was 75% viable and another flask with a pack that was 25% viable they will end up with approximately the same cell count. The 25% viable pack will just take a little longer. So why bother trying to figure out how many cells you have. Just figure out how many mL of starter you need for a given brew...

Really Wow I just don't know where to begin trying to help you. I'll just say your guess would be way off. Oh and the size of your starter is only relevant to the number of  viable cells you have. That's how you determine the size starter you need.

...which just begs the question...How do you determine your initial cell count if your yeast smack/vial is not fresh.  I'm still in contact with Jess at Wyeast on this issue.  If folks here are interested, I'll post his advice.  We already know Jamil's.

[repo]

Here's White Labs advice, btw Jamil co wrote a book with Chris White. I can't believe you have a guy from wyeast claiming 75% viable after almost 120 days. 
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What is the shelf life of White Labs Yeast?

Quick Answer: 4 Months
Long Answer: Yeast is a living organism. As such, it needs to be in the right conditions to survive. Dry yeast can stay alive for one year, but yeast left in liquid form, even though it's a better product in terms of taste and performance, is more perishable. At White Labs, we are constantly working on our recipe to maximize the viability of the yeast in long term storage. The longer we can make the yeast last in the vial, the better shape it will be in for fermentation. After 30 days in the vial, the viability of our yeast is 75-85%, which is very high for liquid yeast. Yeast that is harvested after a brewery fermentation will typically have a viability of less then 50% after 30 days. Our high viability is due to the health of the yeast and nutrient content of our liquid at packaging.  After 6 weeks, lag time before active fermentation is usually between 15-20 hours.  The shelf life for White Labs Yeast is four months.  Yeast used after this point is usually fine, but lag times will be longer. There will be living yeast in most vials for 6-12 months, so if a starter is made to activate the yeast, successful fermentations can be carried out with aged yeast.

 
 

[Poobah58]

A. I don't need help.
B. I posted this elsewhere. I just started up a Wyeast Farmhouse Ale that was almost 4 years old. How viable do you think that was? I started on a stir plate with 500 ml of 1.040 starter. It took 5-6 days to eat up all the sugar. I then stepped up to 1.6L. it took another 4-5 days. I then cooled for 2 days, decanted and added another 2L two days before pitch. It was just about done when I pitched into 15 gallons. That's 3.6L/15 gallons of 1.050 beer. It was rocking within 2 hours and was just about done in 4-5 days!

Like I said, who gives a crap about yeast count. It only takes 1 cell to go thru 2 liters worth of starter. When it's done, you have a boatload of viable cells that will make any beer taste great!

[repo]

A. I'm sorry to hear that
B. Not very viable and possibly useless, irrelevant post.
C. Completely and entirely false

[narvin]

It only takes 1 cell to go thru 2 liters worth of starter. When it's done, you have a boatload of viable cells that will make any beer taste great!

Well, that's not true.  But in practice if you are doing stepped starters, you may not see as much of a difference with low or high viability yeast.  Even with a stirplate, there's a maximum number of divisions you'll get before the yeast switch over to fermentation and/or crap out.  One cell won't grow in 2L of wort, for multiple reasons, but if you start small you should be able to step up any amount of yeast.  Starting from a plated culture, you can begin with 50ml or so.

[Poobah58]

OK, maybe 2 cells...