Nanometer (nm)
One-billionth of a meter: the unit nanotechnology is measured in.
A nanometer is one-billionth of a meter. A human hair is roughly 80,000 to 100,000 nanometers wide and a strand of DNA is 2.5 nanometers across, according to the US National Nanotechnology Initiative. Start here has a ruler from a sheet of paper down to a gold atom.