What do the BSR and its top % mean?

BSR (Best Sellers Rank) is where the product ranks in its main Amazon category. The lower the number, the better it sells.

The top % puts that rank in context. 236K (1%) means the product is ranked about 236,000th, which puts it in the top 1% of its category. A rank of 236,000 is very good in a category with tens of millions of products and poor in a small one, and the percentage lets you compare the two.

How the % is worked out

It's the rank divided by the number of products in the main category, on that marketplace (the United States and Canada each have their own figures), rounded to a whole number. Very small categories don't show a percentage.

Setting a maximum

Set a Max BSR % in Settings > Seller Settings and the BSR turns red on any product ranked outside it.

To see how the rank has moved over time, look at Charts and Ranks & Prices (reading them).