Petameter to Micrometer

The micrometer (micron) is a unit of length equal to 10⁻⁶ meters, or one millionth of a meter.

1 µm = 10⁻⁶ m = 1,000 nm = 0.001 mm. One millimeter equals 1,000 micrometers.

To convert µm to mm: divide by 1,000. To convert µm to inches: multiply by 3.937 × 10⁻⁵.

Measuring human hair thickness (~70 µm), red blood cells (~7 µm), bacteria (1–10 µm), and machining tolerances.

A typical bacterium is about 1–2 µm long, while a human red blood cell has a diameter of about 7 µm.

Writing 'um' instead of 'µm' in formal contexts. Also confusing micrometers (the unit) with micrometers (the measuring tool).

The limit of human vision is about 40 µm — anything smaller requires a microscope.