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.

Radius

A finite measured or assumed value, expressed in µm.

The implementation follows this calculation rule: Compute the volume of a spherical cell in femtoliters, where one cubic micrometer equals one femtoliter.^[1]

Volume

The calculated volume in fL.

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.

• Cell Surface Area Sphere

  Compute the surface area of a spherical cell from its radius in micrometers.

• Cell Diameter From Area

  Derive the diameter of a spherical cell from its surface area in square micrometers.

• Cell Dilution C1V1=C2V2

  Solve C1V1=C2V2 for the stock volume needed to reach a target concentration.