ISO 20391-1:2026

This document provides standard terminology related to cell counting for biotechnology. This document describes counting of cells in suspension (generally cell concentration) and cells adhered to a substrate (generally area density of cells). This document provides key considerations for general counting methods (including total and differential counting, and direct and indirect counting) as well as for fit for purpose method selection, sources of variability in the measurement process, and data analysis and reporting.

This document is applicable to the counting of all cell types – mammalian and non-mammalian (e.g. bacteria, yeast) cells.

NOTE Several sector or application-specific international and national standards for cell counting currently exist. When applicable, the user can consult existing standards when operating within their scope (e.g. specific measurement techniques or applications).