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 1015 nucleus of an atom (not nucleus of a cell). Rarely used in biology
picometer pm 1012 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 1010 sizes of molecules, wavelengths of light
nanometer nm 109 sizes of very large molecules, substructures and organelles of cells, wavelengths of light
micron or micrometer μm 106 sizes of cells and cellular organelles
millimeter mm 103 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 1 103 105 106 109 1012
picometer pm 103 1 102 103 106 109
angstrom A 105 102 1 101 104 107
nanometer nm 106 103 10 1 103 106
micron or micrometer μm 109 106 104 103 1 103
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*1015
to
1.5*1014
1.5
to
15
1.5*103
to
1.5*102
1.5*105
to
1.5*104
1.5*106
to
1.5*105
1.5*109
to
1.5*108
1.5*1012
to
1.5*1011
diameter of atom (varies with element) = twice the atomic radius 5*1011
to
6*1010
5000
to
60000
50
to
600
0.5
to
6
0.05
to
0.6
5*105
to
6*104
5*108
to
6*107
thickness of lipid bilayer 109
to
108
106
to
107
1000
to
10000
10
to
100
1
to
10
103
to
102
106
to
105
wavelength of visible light in vacuum (wavelength depends on color) 4*107
to
7*107
4*108
to
7*108
4*105
to
7*105
4000
to
7000
400
to
700
0.4
to
0.7
4*104
to
7*104
diameter of prokaryotic cell (varies based on organism) 106
to
105
109
to
1010
106
to
107
104
to
105
1000
to
10000
1
to
10
103
to
102
diameter of eukaryotic cell (varies based on organism and cell type) 105
to
104
1010
to
1011
107
to
108
105
to
106
104
to
105
10
to
100
0.01
to
0.1