What is BSR (Best Sellers Rank)?

Amazon's demand signal: how recently and often a product sells in its category.

BSR - Best Sellers Rank, often just "sales rank" - is the number Amazon assigns to every product in a category based on recent sales. Rank 1 is the category's best seller; a rank in the millions means it rarely sells. The number updates through the day and reacts strongly to recent orders.

A single rank snapshot can mislead: one lucky sale can spike a slow product's rank for a day. That is why sourcing decisions read the rank history over weeks and months, not the number in front of you - a product that holds a low rank steadily is demand you can rely on; a one-day spike is not.