Determining cell count when starting from plates

Here is the scenario:
1) inoculate 10 mL of 1.040 wort with loopful of yeast from an agar plate; 24 hours with aeration.
2) step up to 100 mL of 1.040 wort; 24 hours on stir plate.
3) step up to 1 L of 1.040 wort; 24 hours on stir plate.

What is the theoretical cell count? The online calculators don't seem to account for this scenario. Perhaps realistically, most of them start with packets of yeast and account for viability of the packet. I'm thinking maybe the braukaiser calculator comes the closest to reality? If I put in 1 billion cells as the starting cell count, the calculator gives 161 billion cells for a 1 L 1.040 gravity starter on a stir plate. Using the same inputs, the C. White stir plate calculator gives 7 billion cells (both calculations performed here: http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/). One of these has to be wrong because the difference is ridiculously big.

Any thoughts?

This may help you determine the amount of cells you will have after propagating. Check out figure 3 and the information right below it. I haven't used it personally yet but when I start propagating my yeast from slants I will use this information.

If you view Figure 1 in the link provided, that would suggest a cell count of 270-370 billion in a liter's worth of media (i.e., 1000mL of slurry at 270-370 million per mL). Now we have three vastly different cell counts:
1) Braukaiser = 161 billion
2) C. White = 7 billion
3) Maltose Falcons cell count = 270-370 billion.

lshaner said:

If you view Figure 1 in the link provided, that would suggest a cell count of 270-370 billion in a liter's worth of media (i.e., 1000mL of slurry at 270-370 million per mL). Now we have three vastly different cell counts:
1) Braukaiser = 161 billion
2) C. White = 7 billion
3) Maltose Falcons cell count = 270-370 billion.

Click to expand...

Apologies if I've misunderstood what you mean, but a 1L starter does not end up as 1L of slurry (at any rate 270 millions cells/ ml multiplied by 1000ml is 2.7 trillion cells!) The only way to know for sure is a manual cell count via microscopy, but there are others ways of estimating. For what its worth, I've always used braukaiser's/brewers friend calculator, but admittedly I haven't yet checked my results with a microscope to correlate!

Neoprene said:

at any rate 270 millions cells/ ml multiplied by 1000ml is 2.7 trillion cells!

Click to expand...

270 million == 2.7 x 10^8

x 10^3 = 2.7 x 10^11 == 270 billion

(in American English, where 10^9 == 1 billion and 10^12 == 1 trillion)

my 2 cents, i start from glycerol stocks or plates often. i try to get a rough estimate of cell count without counting cells by:
1. looking at a white labs vial, when all the yeast is at the bottom and out of suspension. that volume of clean slurry contains in the ballpark of 100 billion (10^11) cells. i forget ~what volume that is on average, 5 ml or so? i have that info somewhere at home.... but then using that volume as a reference, from your 100ml culture you can estimate cell count by slurry volume, and then use an online calculator to estimate growth from the next culture. that gets you away from the huge uncertainty of number of cells input from picking colonies.
2. or, use the mr malty calculator and set the non-yeast matter slider to the low extreme. with all the to-ing and fro-ing of discussion on what is the best pitching rate (great that people are discussing it but often hard to know where to begin), at least these approaches will give you a rough idea, and you can decide if you want to use more or less based on results

corax said:

270 million == 2.7 x 10^8

x 10^3 = 2.7 x 10^11 == 270 billion

(in American English, where 10^9 == 1 billion and 10^12 == 1 trillion)

Click to expand...

Ahh, apologies! I'm in the uk, forgot you guys on that side of the pond are a bit fruity with your definitions of billions and trillions!
EDIT: I retract that! Turns out my maths is crap! The joys of calculating yeast numbers on my phone when I should be working!