Our sales estimates are calculated using multiple crowd sourced data channels.
The sales estimates exist just to provide an indication, a rough idea, of how well these products are selling.
It is important to remember that any kind of sales figure that a software gives you is an estimate and is not 100% accurate.
As a result of that we advise that you only use sales estimates for comparative purposes, as in don't make your product decisions based on sales estimates but you can use it to compare products eg. "this market has higher sales estimates so I think it's better" instead of "this market has high sales estimates so I will go for it"
At the end of the day the golden metric is Best Seller Rank (BSR) so we advise prioritising that over everything else, this is also why our software uses BSR for its instant demand score analysis.
When looking up your own products sales estimates it is important to remember that the sales estimate is based on the reported BSR being consistent for a month. When your product first launches your BSR is going to vary a lot, so there is no way a software can provide an accurate sales estimate.
Furthermore you should also note that the sales estimate assumes the BSR being consistent for a month, say for example you achieve a BSR of 1000, you need to hold that BSR for a month so that your sales inside of seller central truly show the sales of a 1000 BSR product.
You may be wondering why the sales estimates for some products are the same. In our data analysis we found that the sales made of eg. a BSR 230 product and a BSR 245 product were so close together, there was almost no difference. As a result of this we chose to group BSRs by 25 to speed up the software. This means that eg. all BSRs between 75-100 will report the same number of monthly units sold.