**neper**

##### Non-SI unit accepted for use with SI

Name | Symbol | Quantity | Value in SI units | |

neper | Np | logarithmic ratio | ||

## DefinitionThe 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.