Growth Rate Calculator
Enter Time & Measurement Points (min 3, max 10)
📊 Growth Rate Results
Specific Growth Rate (µ)
—
Doubling Time
—
generation time
Log Phase Points
—
used for µ calculation
R² (Fit Quality)
—
1.0 = perfect log-linear fit
Max OD / Count
—
highest measured value
Data Table with ln(N)
| Time | OD / Count | ln(N) | Phase |
|---|
How to Use the Growth Rate Calculator
Enter at least 3 time-point measurements of OD600 or cell density. The calculator performs linear regression on ln(N) vs time to identify the exponential (log) phase and calculate the specific growth rate µ.
- Time points: Record evenly spaced measurements throughout the growth experiment.
- OD600 range: For accurate results, use only OD600 values between 0.05 and 1.0 (linear range).
- More points = better accuracy: 5–8 points covering the log phase gives the most reliable µ value.
Growth Rate Calculation Method
During exponential growth: ln(N) = ln(N₀) + µ × t
µ is the slope of ln(N) vs time (linear regression)
Doubling time td = ln(2) / µ = 0.693 / µ
R² measures fit quality:
R² ≥ 0.99 → Excellent log-linear fit
R² 0.95–0.99 → Good fit
R² < 0.95 → Poor fit — check for lag/stationary phase points
µ is the slope of ln(N) vs time (linear regression)
Doubling time td = ln(2) / µ = 0.693 / µ
R² measures fit quality:
R² ≥ 0.99 → Excellent log-linear fit
R² 0.95–0.99 → Good fit
R² < 0.95 → Poor fit — check for lag/stationary phase points
Bacterial Growth Phases
- Lag phase: Cells adapt to media — little or no increase in OD600.
- Exponential (log) phase: Rapid doubling — OD600 increases exponentially. Use these points for µ.
- Stationary phase: Growth slows as nutrients deplete — OD600 plateaus.
- Death phase: Cell lysis begins — OD600 may decrease.