| meter | m | one (100) meter | an adult human averages 1.7m in height, and the length from the floor to the ceiling is typically 2.4m |
| centimeter | cm | one hundredth (10-2) of a meter | the width of a coffee bean, a fingernail, a thumbtack, or a pea |
| millimeter | mm | one thousandth (10-3) of a meter | the thickness of a credit card, a pencil tip, or the width of a blade of grass |
| micrometer | µm | one millionth (10-6) of a meter | the thickness of a bacteria, a strand of spider silk, plastic cling wrap, a human hair, or a piece of paper |
| nanometer | nm | one billionth (10-9) of a meter | the thickness of a carbon nanotube, a sucrose molecule, a DNA helix, or a phospholipid bilayer |
| picometer | pm | one trillionth (10-12) of a meter | roughly the thickness of a helium atom |
| femtometer | fm | one quadrillionth (10-15) of a meter | roughly the diameter of a neutron |
Or see these for an overview: