nanometre

Everyday

A unit of length: one billionth of a metre (0.000000001 m). Symbol: nm. tree →

In the lessons

A science and maths word for very, very tiny things: atoms, molecules, viruses and the wavelength of light are measured in nanometres. Computer chips have parts only a few nanometres across. In maths: 1 metre = 1,000,000,000 nm; 1 millimetre = 1,000,000 nm.

Examples

• A nanometre is a billion times smaller than a metre. tree →
• A human hair is about 80,000 nanometres wide. tree →
• Visible light has wavelengths of about 400 to 700 nanometres. tree →
• Some viruses are about 100 nanometres across. tree →
• Computer chips have tiny parts measured in nanometres. tree →
• Your fingernails grow about one nanometre every second. tree →
• We use nm as the symbol for nanometre. tree →

Note

UK, Canada, Australia and NZ spelling "nanometre"; US spelling "nanometer". Symbol "nm" (not "nM", which is a chemistry unit). Prefix "nano-" means one billionth. In maths problems: divide nanometres by 1,000 to get micrometres, by 1,000,000 to get millimetres.