Size measures for items related to cells
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 | nucleus of an atom (not nucleus of a cell). Rarely used in biology | |
| picometer | pm | 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 | sizes of molecules, wavelengths of light | |
| nanometer | nm | sizes of very large molecules, substructures and organelles of cells, wavelengths of light | |
| micron or micrometer | m | sizes of cells and cellular organelles | |
| millimeter | mm | 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 m | Number of mm |
|---|---|---|---|---|---|---|---|
| femtometer | fm | 1 | |||||
| picometer | pm | 1 | |||||
| angstrom | A | 1 | |||||
| nanometer | nm | 10 | 1 | ||||
| micron or micrometer | m | 1 | |||||
| millimeter | mm | 1 |
| Item | Number of meters | Number of fm | Number of pm | Number of angstroms | Number of nm | Number of m | Number of mm |
|---|---|---|---|---|---|---|---|
| diameter of atomic nucleus (varies with element) = twice the nuclear radius | to |
1.5 to 15 |
to |
to |
to |
to |
to |
| diameter of atom (varies with element) = twice the atomic radius | to |
5000 to 60000 |
50 to 600 |
0.5 to 6 |
0.05 to 0.6 |
to |
to |
| thickness of lipid bilayer | to |
to |
1000 to 10000 |
10 to 100 |
1 to 10 |
to |
to |
| diameter of prokaryotic cell (varies based on organism) | to |
to |
to |
to |
1000 to 10000 |
1 to 10 |
to |
| diameter of eukaryotic cell (varies based on organism and cell type) | to |
to |
to |
to |
to |
10 to 100 |
0.01 to 0.1 |