OD600 to Cell Density
Cell density from an OD600 reading, in cells per mL.
Example
You enter
- OD600 reading 0.5
- Conversion factor (cells/mL per OD) 800000000
- Dilution factor 1
You get
- Cell density 400000000 cells/mL
Details, formula, and sources
Cells/mL = OD600 x conversion factor x dilution, with a linear-range flag above OD ~0.8. Conversion factor is strain- and instrument-specific (user-supplied). Lab SOP governs.
cells/mL = OD600 * factor * dilution, where the OD-to-cells factor is strain- and instrument-specific. Linear range is typically OD < ~0.8 (dilute and re-read above it).
Standard microbiology spectrophotometry; the OD600-to-cell-density relation, by practice.
Public method; the conversion factor is established per strain and instrument by the lab (no universal constant).
Verify protocol against your lab's SOP before pipetting. A miscalculated dilution can ruin a run or a sample.
Field names used by the API: od600, factor_cells_per_od, dilution, cells_per_ml
- Conversion factor strain- and instrument-specific (e.g., E. coli ~8e8 cells/mL per OD600 on a typical spectrophotometer); user-suppliedlab calibration
- Linear range OD600 < ~0.8; above it, dilute and re-readspectrophotometry practice