Cell Culture & Doubling Time Tracker
Population doubling time, confluence tracking and passaging schedule forecasting for adherent and suspension culture.
How it works
Population doubling time is calculated as Td = t × ln(2) ÷ ln(Nt/N0), where N0 and Nt are the cell counts at the start and end of an interval of length t. Confluence trajectories are projected forward from the current growth rate to forecast when a flask will need passaging.
Frequently asked questions
How do you calculate cell doubling time?
Doubling time equals the elapsed time multiplied by ln(2), divided by the natural log of the ratio of final to initial cell count. For example, growing from 2×10⁵ to 8×10⁵ cells in 48 hours gives 48 × 0.693 ÷ ln(4) = about 24 hours. Measure across the exponential growth phase only — rates calculated across lag or plateau phases are misleading.
At what confluence should I passage cells?
Most adherent lines are passaged at 70–90% confluence, before contact inhibition and nutrient depletion alter their behaviour. Letting cultures reach full confluence repeatedly changes growth rate, morphology and gene expression, and for many lines it drives differentiation or senescence. Consistency matters as much as the exact number: passaging at the same confluence each time keeps experiments comparable.