BSR
Also known as: Best Seller Rank, Sales Rank
Amazon's ranking of how a product's sales velocity compares to other products in its category.
BSR (Best Seller Rank, sometimes "Sales Rank") is the ranking Amazon assigns to every product within its main category and any sub-categories it belongs to. BSR #1 means it's the top-selling item in that category. BSR is updated continuously based on recent sales velocity, weighted toward the most recent hour but smoothed over a longer window to prevent extreme oscillation.
Why sellers care: BSR is a direct proxy for sales velocity. Sourcing tools like SellerAmp, Keepa, and SellerVault's product scanner use BSR (alongside historical price and BSR trend data) to estimate monthly sales for products you're considering buying. A product with stable BSR in the top 1% of its category is selling consistently; one bouncing between top 10% and top 50% is unstable.
BSR is category-relative. A BSR of 5,000 in Books (which has millions of products) is much higher velocity than a BSR of 5,000 in Patio Furniture (which has thousands). Always look at BSR alongside the category size and the historical BSR trend, not the absolute number alone.