Calculate split ratios, seeding densities, and passage schedules for adherent and suspension cell lines. Growth curve prediction with doubling time modeling. Data never leaves your browser.
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Load example cell passaging data to see the full workflow
| Passage | Time | When |
|---|---|---|
| P1 | 48h | Day 2, ~0h |
| P2 | 96h | Day 4, ~0h |
| P3 | 144h | Day 6, ~0h |
| P4 | 192h | Day 8, ~0h |
| P5 | 240h | Day 10, ~0h |
When to use
Do not use for
The calculator estimates cell count from confluence percentage, which is inherently approximate. For experiments where seeding density matters (transfection, drug screens), use a hemocytometer or automated counter for the actual count.
Early-passage cells often grow slower than established cultures. After many passages (>30 for most lines), doubling time may increase and growth becomes unreliable. Track your own doubling times rather than relying on published values.
Freshly passaged cells experience a lag phase of 2-6 hours while they attach and equilibrate. The exponential model starts after this lag, so actual time to confluence may be slightly longer than predicted.
Over-trypsinization damages cell surface proteins and can affect doubling time. Use the minimum exposure time needed for detachment. Consider using TrypLE or Accutase for sensitive cell lines.
Exponential growth model N(t) = N₀ 2^(t/Td). Cell counts estimated from confluence percentage vessel area cell line density at 100% confluence. Split ratios computed from harvested:seeded cell ratio.
Last validated 2026-04-05. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience Cell Passaging Calculator (v1.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/cell-passaging-calculator
Freshney RI. Culture of Animal Cells. 7th ed. Wiley-Blackwell; 2016.
The split ratio describes the dilution factor at passage. A 1:4 split means seeding one-quarter of the harvested cells into each new vessel.
Split ratio = (cells harvested) / (cells seeded per vessel)
Higher ratios (1:10, 1:20) are economical but delay confluence. Lower ratios (1:2, 1:3) maintain faster growth but require more frequent passages. Most standard protocols use 1:3 to 1:6 for routine maintenance.
Cells in log-phase follow exponential growth:
N(t) = N₀ 2^(t/Td)
Where N₀ is the initial count, t is time in hours, and Td is the doubling time. This model applies during log-phase growth (approximately 20-80% confluence). At very low or very high densities, growth deviates due to lag phase and contact inhibition, respectively.
