Year old yeast

I have a few vials of white labs yeast that are 10-11 months old. I plan on making a starter to see if they're still viable, and then stepping them up if so. My question is what size starter should I use for the first step? There seems to be a lot of conflicting and unsure information about long term yeast viability, and I want to make sure the inoculation rate isn't too low for the first step. Or does it even matter for the first step?

Yes there are many schools of thought on this one but I suspect whatever path you take will get a result.
If you believe YeastCalc then you have only around 1% viability while Mr Malty suggests 10% viability.
Some who have conducted their own tests suggest these figures are too conservative and the figure would be significantly higher.

If I was aiming for around 200Bn viable cells.

If there is in fact only 1 Bn viable cells as YeastCalc suggests then I would probably do it in 3 steps
0.5L , 1L then 2L

If I believed Mr Malty's suggestion of 10Bn cells then I would probably still start with 0.5L then a 2L.


It would be great if you tried different options of starter size and SG of wort and report back the results. I for one would be most interested.

Calculate the efficiency of the yeast. That will help you determine it's viability.


I personally would go straight to 2 L starters and castle based off a 1050 brew.

Thanks guys. I used a 1L starter for the first step on the first vial, and it started to take off at the 30hr mark. That kind of lagtime tells me I should have started smaller. I think I'll start with 500mL for the others, and then step up from there.