Cell Bank Calculator

Building a cell bank means growing a small starting population up to millions of vials' worth of cells and freezing them down in uniform aliquots, and the math behind that is exponential growth in reverse. This calculator first works out the total cell mass required — cells per vial times the number of vials you want, divided by expected post-thaw viability, since some fraction of frozen cells won't survive the freeze-thaw cycle and you need to bank enough to compensate. It then computes the number of population doublings needed to get from your starting cell count to that total using log2(total cells / starting cells), since each doubling exactly doubles the population.

Multiplying doublings by your doubling time (the hours it takes a culture to double, typically 18-30 hours for common mammalian lines) gives total expansion time, and dividing doublings by two estimates the number of passages needed, on the assumption that a typical 1:4 split each passage corresponds to roughly two doublings of regrowth. Freeze volume and freeze medium are then just vial count times volume per vial, with a flat 10% overage added to the medium figure to cover pipetting losses during the cryopreservation fill. The calculation assumes clean, unbroken exponential growth for the entire expansion — no lag phase after thaw, no growth-rate slowdown as cultures approach confluence, and a constant doubling time throughout — so treat the expansion-time and passage-count outputs as optimistic planning estimates rather than a guaranteed timeline, and pad your real schedule accordingly.