What is sales velocity?

How many units a listing actually sells per week or month.

Sales velocity is the count behind the rank: how many units a listing sells in a period. Rank says "this product sells"; velocity says how many you can realistically expect to move - which sets how many you should buy and how fast your capital comes back.

Velocity is estimated from rank history and its movements, and it must be divided by the number of competitive sellers on the listing: a listing selling thirty units a week with ten Buy Box rotations feeds each seller three. Buying a month of velocity, not a year, is the standard discipline.