How to Read a Keepa Price Chart

Keepa is the single most useful free tool for Amazon arbitrage. But its charts look busy until you know what each line means. This guide breaks down how to read one so you can tell a genuine opportunity from a trap.

What is Keepa?

Keepa is a price-tracking service that records the history of nearly every product on Amazon — price, who is selling it, and how well it sells — going back months or years. It runs as a browser extension and an API. For an arbitrage seller, a Keepa chart answers the two questions that matter most: is this price normal or unusually low, and does this product actually sell?

The price lines

A Keepa chart overlays several lines. The three you will use most are:

• Amazon (orange) — the price when Amazon itself is selling. Gaps in this line mean Amazon was out of stock. This line matters a lot: when Amazon is on a listing, competing on price is hard.
• New / third-party (blue) — the lowest price from third-party sellers offering a new item. This is roughly the market you would be competing in.
• Buy Box (pink) — the actual winning price shown to shoppers, including Amazon and third-party offers. Because most sales go through the Buy Box, this is the price you should usually benchmark against.

Colours and visible lines depend on your Keepa settings, but the meanings stay the same. Always confirm which line you are reading before drawing conclusions.

Sales rank (BSR) as a velocity proxy

The green line is the Best Sellers Rank (BSR). A lower number means the product is selling faster within its category. You cannot read exact units from BSR, but you can read the shape of the line.

Look for the drops — each time the green line jumps down sharply, that typically marks a sale (or a batch of sales). A chart with frequent, regular rank drops suggests steady demand. A flat line with rare drops suggests a slow seller, no matter how tempting the margin looks. Many sellers count rank drops over the last 30 or 90 days as a rough velocity estimate.

Genuine dip vs stable low

One of the most common beginner errors is buying into a price that only looks low for a moment. Use the history to tell the difference:

• A genuine dip is a temporary drop below a clear, established normal price — the kind you can buy under and sell back up to.
• A stable low is a price that has been trending downward for weeks. If the Buy Box has been steadily falling, today's price may simply be the new normal — and it could fall further after you buy.

The Amazon-in-stock signal

Pay close attention to the Amazon (orange) line. If Amazon is frequently in stock and holds the Buy Box, a third-party seller will struggle to win sales at a healthy price. If the orange line shows long out-of-stock gaps, third-party sellers have had room to operate. A listing where Amazon dips in and out is a re-entry risk: you may buy while they are out, only for them to return and crush the price.

The 30 / 90 / 180-day averages

Keepa shows average prices over the last 30, 90 and 180 days. These are your sanity check. Compare today's Buy Box against the 90-day and 180-day averages: if the current price sits well below a steady long-run average, you may have found a real dip. If the averages are themselves falling each period, the product is in decline and the "deal" is riskier than it looks. Longer windows smooth out noise; shorter windows show the recent trend.

DYOR: this guide is for general information only and is not financial advice. Keepa history describes the past and does not predict future prices or sales. Always check the chart and confirm the numbers yourself before buying.