Originally Posted by 907_fellow
I've got a massive keezer (19.7 cf) so cold crashing anything isn't an issue. But ****, 5.7 L? That's massive. Could I make 3L starter, put it in the fridge, then make another 3L starter the next day, and pitch both of brew day? Is it okay to let one sit for a few days before pitching? I kno the cell count will drop a bit in a few days but that's why I would make two 3L starters to compensate for that loss.
Like I said above, yeastcalc will show you how to step up starters. Look at the cell count it recommends for the OG and batch size you're making, then input your yeast info (dry yeast is about 230billion cells, liquid is ~100b). The first starter you set up the oxygenation method and size you'd like to make, it will tell you how many cells you'll end up with. If it's not enough for the original cell count prescribed, add another starter below the first one and play with the size until it comes out to as many or slightly more than you need. My example above was done on yeastcalc and is relevant for your batch, based on the info you gave, and it only uses one batch of yeast.
if you're short on time, sure, you can make two starters from two vials and do it that way...just costing yourself another $8 or whatever you pay for vials.