A nanogram is a unit of mass equal to one billionth of a gram.

The abbreviation for nanogram is "ng"(without quotes).

Nanogram per liter (ng/L) and milligram per liter (mg/L) are both units of measurement used to express the concentration of a substance in a liquid. The main difference is in their scale: nanogram per liter is a smaller unit of measurement than milligram per liter. 1 milligram (mg) is equal to 1,000,000 nanograms (ng), so if a substance is measured in ng/L, it would be a much smaller concentration compared to if it were measured in mg/L.

A nanogram is smaller. 'Micro' means one-millionth, 'Nano' means one-billionth. micro means one-millionth. nano means one-billionth. There are 1,000 nanograms in a microgram, so nanograms are smaller.

There are 1000 picograms in a nanogram.