The terms you actually need when you're vetting products to sell on Amazon — defined in one sentence, then explained. Built for wholesale and arbitrage sellers who read Keepa charts and supplier lists, not textbooks.
A product's Best Sellers Rank (BSR) is the number Amazon assigns within a category to show how well it is selling relative to other products in that same category, where #1 is the best-selling item.
Keepa is a third-party service that tracks the price, Buy Box, and sales-rank history of Amazon products over time and presents it as charts and exportable data.
Out-of-stock % (OOS)
Out-of-stock percentage is the share of time a product or its Buy Box has had no available offer over a given period; a high figure can signal supply gaps and opportunity, or an unstable, hard-to-keep-live listing.
Sell-through rate
Sell-through rate is how quickly inventory sells in a period — units sold divided by units available — used to judge how fast a product will move and how soon your cash comes back.
Amazon FBA fees are the charges Amazon deducts when you sell using Fulfillment by Amazon — chiefly the referral fee (a category-based commission) and the fulfillment fee (a size- and weight-based pick, pack, and ship charge).
Return on investment (ROI) for an Amazon product is your net profit divided by your total cost, expressed as a percentage — how much you earn back on every dollar you put in.
Referral fee
The referral fee is the commission Amazon takes on each sale — a category-based percentage of the total sale price (most categories are 15%), charged regardless of how the order is fulfilled.
Fulfillment fee
The FBA fulfillment fee is the flat per-unit charge Amazon takes to pick, pack, and ship an order, set by the product's size tier and weight.
Size tier
An Amazon size tier is the dimensional and weight bucket (such as Small Standard, Large Standard, or an oversize tier) that Amazon uses to set a product's FBA fulfillment fee.
True cost (landed cost)
True cost, or true landed cost, is the all-in cost of getting one unit sold on Amazon — product price plus prep, inbound shipping, Amazon fees, VAT, and expected returns — not just the supplier's quoted price.
Sourcing models
Online arbitrage (OA)
Online arbitrage is sourcing products from online retailers at a low price to resell on Amazon for a profit, typically by screening large lists of retailer deals for products that clear fees with margin to spare.
Wholesale sourcing
Wholesale sourcing is buying products in bulk directly from brands or authorized distributors at trade prices to resell on Amazon, usually working from supplier price lists of hundreds or thousands of items.
The Buy Box is the boxed 'Add to Cart' / 'Buy Now' area on an Amazon product page that completes the default purchase, awarded to one seller at a time among those sharing the same listing.
ASIN
An ASIN (Amazon Standard Identification Number) is the 10-character alphanumeric code Amazon assigns to every product in its catalog to identify that specific listing.
Offer count
Offer count is the number of sellers currently listing the same product; a high or rising count signals competition — a 'flooded' listing — that compresses price and splits Buy Box share.
See these metrics across your whole list
Gridwinner reads your Keepa exports and supplier files locally, then calculates fees, true cost, and ROI for every product at once.