Is nanometer the smallest unit of length?

Nano is not the smallest unit of length.

Pimi

Pimi or pm is the unit of length, and 1 pimi is equivalent to one hundredth of 1 meter. Sometimes it is called a micron in atomic physics.

transformational relation

0.00 1 nm = 1 picometer

Nanometer

The femto meter (or fm) is the unit of length, and 1 femto meter is equivalent to10-15m.

transformational relation

0.000 00 1 nanometer (nm) = 1 femtometer.

Nanometer is the unit of length, and the symbol is nm. 1nm =1nm = 10 angstrom (billionth of a meter), which is about the length of10 atoms. Suppose that a hair has a diameter of 0.05 mm and is divided into 50,000 hairs on average in the radial direction, and the thickness of each hair is about 1nm.

It can be seen that the femto meter is the smallest at present.