Helium 10 doesn’t calculate sales using BSR alone. It blends only with,
Category-specific sales velocity curves
Historical BSR changes
Competitor inventory movement
Average selling price patterns
Time-of-day BSR variations
Internal demand smoothing models
Even small shifts in the category’s velocity (for example, during holiday traffic spikes) cause the model to recalculate estimated sales. That means, your ASIN’s BSR might stay stable, but the category’s overall demand may change, which affects the model’s output.
So, Amazon’s BSR is relative, not absolute. If the entire category speeds up or slows down, your product’s “estimated sales” shift even without your BSR changing.
You have to treat Xray’s revenue and sales as trend indicators, not literal numbers.
And compare ASINs to each other, not to the absolute estimate.