Cell growth / seeding calculator — Calculate population doubling time (Td) from two cell counts and elapsed time, and compute seeding density (cells/well) for a given plate format. Formula: Td = t × ln2 / ln(N/N₀).

(1) Measure doubling time when introducing a new cell line (e.g., HEK293 ~24h, HeLa ~22h, CHO ~16h) (2) Plan passaging (predict time to next 80% confluency) (3) Auto-calc seeding density for 96/24/12/6-well plates, T25/T75/T175 flasks (4) Estimate cell count at treatment time for drug experiments

[Doubling Time mode] ① N₀ (initial cell count by hemocytometer/Countess) ② N (cell count after time t) ③ t (elapsed hours) → Td auto-displayed [Seeding mode] ① Choose plate format (96/24/12/6-well, T25/T75/T175, etc.) ② Target seeding density (cells/cm² or cells/well) ③ Cell stock concentration (cells/mL) → Volume of cell suspension per well + dilution amount

Example 1) Doubling time measurement → N₀ = 2×10⁵, N = 8×10⁵, t = 48h → Td = 48 × ln2 / ln(4) = 48 × 0.693 / 1.386 = 24h Example 2) HEK293 in 6-well, target 70% confluence the day after transfection → Plate: 6-well (9.6 cm²/well), Target: 3×10⁵ cells/well → Stock: 1×10⁶ cells/mL → Add 300 µL stock + 1.7 mL medium per well