Bacterial Growth and Doubling Time Calculator
Calculate bacterial doubling time, growth rate constant, and number of generations from initial and final cell counts or OD600 absorbance readings.
Bacterial Growth Results
Doubling Time The time required for a bacterial population to double in number.
td = t × ln(2) / ln(N / N0)
Where:
- t = elapsed time (hours)
- N = final cell count (or OD600)
- N0 = initial cell count (or OD600)
- ln = natural logarithm
Number of Generations n = log2(N / N0) = ln(N / N0) / ln(2)
Growth Rate Constant (k) k = ln(N / N0) / t — units: per hour
Predicting Future Count N(t) = N0 × 2^(t / td)
Common Reference Doubling Times
- E. coli: ~20 minutes (ideal conditions)
- S. aureus (Staph): ~30 minutes
- Lactobacillus: ~60 minutes
- Mycobacterium tuberculosis: ~15–20 hours
OD600 Mode Optical density at 600 nm is proportional to cell density. Use initial and final OD600 readings exactly like cell counts — the math is identical.