OD600 Cell Density Calculator
🔬 OD600 Results
Cell Density
—
Corrected OD600
—
after dilution correction
Conversion Factor
—
cells/mL per OD unit
Scientific Notation
—
cells/mL
Log₁₀ Density
—
log cells/mL
How to Use the OD600 Cell Density Calculator
Enter your OD600 absorbance reading and select your organism to get an estimated cell density. If you diluted the culture before measuring, enter the dilution factor to get the corrected density.
- OD600 Reading: Absorbance measured at 600 nm wavelength in your spectrophotometer.
- Dilution Factor: If measured undiluted, leave as 1. If you diluted 1:10 before reading, enter 10.
- Conversion Factor: Species-specific constant relating OD600 to cell count. Use presets or enter a custom value from your calibration curve.
OD600 to Cell Density Formula
Cell density is calculated by multiplying the corrected OD600 by the species-specific conversion factor:
Corrected OD600 = Measured OD600 × Dilution Factor
Cell Density = Corrected OD600 × Conversion Factor
Example (E. coli):
OD600 = 0.5, Dilution = 2, Factor = 8 × 10⁸
Corrected OD = 0.5 × 2 = 1.0
Cells/mL = 1.0 × 8 × 10⁸ = 8 × 10⁸ cells/mL
Cell Density = Corrected OD600 × Conversion Factor
Example (E. coli):
OD600 = 0.5, Dilution = 2, Factor = 8 × 10⁸
Corrected OD = 0.5 × 2 = 1.0
Cells/mL = 1.0 × 8 × 10⁸ = 8 × 10⁸ cells/mL
Note: OD600 is linear only up to ~0.4–0.6. Dilute dense cultures to keep readings in the linear range for accuracy.
OD600 Linear Range & Growth Phases
- OD600 < 0.1: Early lag phase — culture adapting to media.
- OD600 0.1–0.4: Early exponential phase — ideal for experiments.
- OD600 0.4–0.8: Mid-log phase — peak growth rate.
- OD600 > 1.0: Outside linear range — must dilute before measuring.
- OD600 > 2.0: Late stationary phase — nutrient depletion likely.