Especially with something as flocculant as 002, you can get at least a rough double-check of the calculator based on mass or volume. Give it a couple days in the fridge to settle out the solids, then pour off as much liquid as possible and measure. If it's really thick slurry, figure 3 billion cells per mL; if it's runny but pours like a liquid 2 billion/mL; if it pours like water 1 billion/mL. You'll certainly be within 50% of your actual cell count, likely much closer.