# neper

##### Non-SI unit accepted for use with SI
Name Symbol Quantity Value in SI units
neper Np logarithmic ratio

### Definition

The neper, symbol Np, is a non-SI unit accepted for use with the SI.

One neper, is equal to the neperian (or natural) logarithm of a ratio between two power quantities of 2:1, or the neperian (or natural) logarithm of a ratio between two root-power quantities of √2:1

The neper is named after the Scottish mathematician John Napier (1550 – 1617), the inventor of logarithms.