What does this number measure?
A living boundary a few nanometres thick. A lipid bilayer and numerous proteins separate the cell from its surroundings. The reference compares membrane thickness, not the width of the fragment drawn.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.
Cell membrane: a schematic cross-section of a lipid bilayer with embedded proteins. Height compares membrane thickness; molecular arrangement and proportions are interpreted.