Size measures for items related to cells

From Cellbio

This page lists order of magnitude estimates for the sizes of various microscopic items that are related to cells. The goal is to give a rough sense of what individual sizes mean, since these are too small for us to compare with our day-to-day intuitions.

Units for length

Units

Unit for length (full word) Unit for length (shorthand) In terms of meters (m) What's it used to measure?
femtometer fm 10−15 nucleus of an atom (not nucleus of a cell). Rarely used in biology
picometer pm 10−12 radius and diameter of an atom or size of a molecule. Used in biology when talking about biological membranes and passage of ions through membranes
angstrom A 10−10 sizes of molecules, wavelengths of light
nanometer nm 10−9 sizes of very large molecules, substructures and organelles of cells, wavelengths of light
micron or micrometer μm 10−6 sizes of cells and cellular organelles
millimeter mm 10−3 Rarely used in cell biology. May be used for tissues and cell clusters

Conversion between units

Unit for length (full word) Unit for length (shorthand) Number of fm Number of pm Number of angstroms Number of nm Number of μm Number of mm
femtometer fm 1 10−3 10−5 10−6 10−9 10−12
picometer pm 103 1 10−2 10−3 10−6 10−9
angstrom A 105 102 1 10−1 10−4 10−7
nanometer nm 106 103 10 1 10−3 10−6
micron or micrometer μm 109 106 104 103 1 10−3
millimeter mm 1012 109 107 106 103 1

Lengths of items related to cell size

Item Number of meters Number of fm Number of pm Number of angstroms Number of nm Number of μm Number of mm
diameter of atomic nucleus (varies with element) = twice the nuclear radius 1.5*10−15-1.5*10−14 1.5-15 1.5*10−3-1.5*10−2 1.5*10−5-1.5*10−4 1.5*10−6-1.5*10−5 1.5*10−9-1.5*10−8 1.5*10−12-1.5*10−11
diameter of atom (varies with element) = twice the atomic radius 5*10−11-6*10−10 5000-60000 50-600 0.5-6 0.05-0.6 5*10−5 - 6*10−4 5*10−8 - 6*10−7
thickness of lipid bilayer 10−9-10−8 106-107 1000-10000 10-100 1-10 10−3-10−2 10−6-10−5
diameter of prokaryotic cell (varies based on organism) 10−6-10−5 109-1010 106-107 104-105 1000-10000 1-10 10−3-10−2
diameter of eukaryotic cell (varies based on organism and cell type) 10−5-10−4 1010-1011 107-108 105-106 104-105 10-100 0.01-0.1
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