Use this calculation for cell-culture or microscopy observations collected with one counting rule, assay gate, calibration, and unit convention. It is suited to documenting dilution, growth, labeling, geometry, or population fractions.

Initial count

A finite measured or assumed value.

Final count

A finite measured or assumed value.

Elapsed time

A finite measured or assumed value, expressed in h.

The implementation follows this calculation rule: Calculate the specific growth rate in inverse hours from two counts.

Specific growth rate

The calculated specific growth rate in 1/h.

Counts and fluorescence measurements can be biased by clumping, debris, segmentation, gating, background signal, saturation, sampling fields, or unequal viability. A calculated percentage does not identify the biological mechanism behind a change. Preserve the input values and units so the result can be audited and recalculated.

Retain representative images or cytometry plots and include biological replicates. Orthogonal viability, proliferation, apoptosis, or direct counting assays can distinguish effects that a single cell metric conflates.

• Doubling Time (PDT)

  Calculate population doubling time as elapsed hours times ln(2), divided by ln(final count / initial count).

• Confluence %

  Compute the percentage of a culture vessel surface covered by cells from occupied and total flask areas.

• Cell Viability %

  Calculate the viability percentage from viable and total cell counts.