Starter Cell Count after Month in the Fridge

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DoubleEh

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About a month ago I made a starter from half a vial of White Labs WLP002. I used roughly 600 ml of 1.040 starter wort in a 2L flask on a stir plate and estimated the cell count to be just over 100 Billion using YeastCalc. I wound up not brewing that weekend and put the flask in the fridge with tightly sealed foil covering the opening. It's been in the fridge for the past 4 weeks. Any thoughts on how many viable cells it might contain now? The plan is to step it back up in another starter and brew a 2.5 gallon batch in a couple of days. Thanks.
 
I read somewhere on this site that it's about a 25% loss per week in the fridge. Assuming you started at 100 billion cells, that would put you at around 31.6 billion cells. That seems really low to me though. Perhaps someone with better information could chime in and confirm or correct me?
 
Thanks. I'll go with that number and if I wind up slightly over pitching that's okay.
 
From cell counts I have done viability doesn't reduce nearly that much over time in the fridge. 5% per week would be a safe estimate, but 1% per week is more realistic. See my blog or book for details.
 
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