Amazon BSR sales estimator
Enter a product’s Best Sellers Rank and get the monthly and daily sales that products at that rank typically make. The curve is fitted to Amazon’s own “bought in past month” figures (2,634 on Amazon US and 1,447 on Amazon AU products measured in the last 90 days) and refit every week, with a separate fit for Australia. Free and no sign-up.
Product details
Estimated demand
Enter a BSR to see the estimate.
LumaiScope reads the measured “bought in past month” figure for a real ASIN when Amazon shows one, and only estimates when it doesn’t. Validate a product free.
How the estimate is made
- Every day LumaiScope records the rank and the “bought in past month” figure for the products it tracks on each marketplace.
- Those pairs follow a power law: sales fall by a roughly constant factor each time rank multiplies by ten. We fit that line per marketplace, and per category once a category has at least 40 measured products.
- Amazon’s figure is a floor (“1K+”), so each point is lifted to the middle of its bucket before fitting. The estimate is a central value, not a minimum.
- The likely range is one standard deviation of the fit’s scatter, which covers about two thirds of products at a given rank.
- The fit is redone every week from the last 90 days of data, so it tracks the market instead of a table someone typed in years ago.
Rank tells you volume, not profit. Once you have a demand figure, run it through the free FBA profit calculator to see what each unit actually earns, and read the guide on validating product demand for the other signals worth checking before you order.
Frequently asked questions
How does the estimator turn a BSR into sales?
Amazon shows a "bought in past month" figure on many listings. LumaiScope records that figure next to the product's rank every day across the products it tracks, then fits a curve through those pairs for each marketplace, and for each category with enough data. Enter a rank and the curve returns the sales that products at that rank typically make.
How accurate is it?
It is an estimate, and we show a likely range for that reason. Amazon's figure is bucketed ("1K+" means at least a thousand), rank is recalculated hourly, and two products at the same rank can sell quite differently. The range covers roughly two thirds of products at a given rank. For a specific product, the measured figure on its listing beats any estimate.
Why do the same ranks give different numbers for the US and Australia?
Rank is relative to every other product in that marketplace's category. Amazon.com.au has far fewer buyers than Amazon.com, so a rank of 5,000 in Australia sits much further down the demand curve. We fit each marketplace on its own data rather than scaling the US curve, which is why the Australian numbers are lower.
Should I use the main category rank or the sub-category rank?
The main category rank. Sub-category ranks are small pools and look flattering. The rank line on a listing reads something like "#4,512 in Kitchen & Dining" followed by sub-category ranks, and the first one is the one to enter here.
How often is the curve updated?
Weekly. Each fit uses the last 90 days of measured pairs, so seasonal shifts in how rank maps to sales show up within a few weeks rather than sitting in a static table for years.
Get the measured number for a real product
Paste an ASIN and LumaiScope reads the listing’s actual sales figure when Amazon shows one, tracks its rank daily from then on, and ends in a plain-English GO / WATCH / NO-GO verdict. Start free, no credit card.
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