You check your Amazon listing and sales have dropped 70% overnight. Nothing changed with your product, your price, or your reviews. You lost the Buy Box. The "Add to Cart" button now belongs to another seller, and your offer is buried under a tiny "Other Sellers on Amazon" link that most shoppers never click. This scenario plays out thousands of times a day on Amazon, and understanding the Buy Box algorithm is the difference between capturing sales and watching them go to a competitor.
The Amazon Buy Box is the white box on the right side of a product detail page that contains the "Add to Cart" and "Buy Now" buttons. When multiple sellers offer the same ASIN (product), Amazon's algorithm decides which seller's offer appears in that box. The winner gets the sale. Everyone else gets almost nothing. Amazon reports that 82% of all Amazon sales go through the Buy Box (widely cited industry estimate), and on mobile (which accounts for over 60% of Amazon traffic), the Buy Box is even more dominant because alternative seller offers require additional taps to find.
Buy Box Algorithm Factors
Amazon doesn't publish the exact Buy Box algorithm, but years of seller data, third-party research from Feedvisor, BuyBoxBuddy, and Jungle Scout, and Amazon's own documentation reveal the key factors and their approximate weight.
| Factor | Impact Level | What Amazon Evaluates | How to Win |
|---|---|---|---|
| Fulfillment method | Very High | FBA vs. FBM vs. SFP (Seller Fulfilled Prime) | FBA wins the Buy Box significantly more often than FBM. Amazon trusts its own fulfillment network to deliver on time. SFP can compete with FBA if your metrics are strong. |
| Landed price | Very High | Product price + shipping cost (the total the customer pays) | You don't need the absolute lowest price, but you need to be competitive. Amazon compares your landed price against other offers. Being 2-5% above the lowest price is often still Buy Box eligible if your other metrics are strong. |
| Order Defect Rate (ODR) | High | Negative feedback rate + A-to-Z claims + chargeback rate | Keep ODR below 1% (Amazon's threshold). Above 1% and you risk account suspension, not just Buy Box loss. Respond to all negative feedback within 24 hours. Resolve A-to-Z claims proactively. |
| Shipping speed | High | Promised delivery date shown to customer | Faster delivery wins. FBA sellers automatically get Prime 1-2 day shipping. FBM sellers should offer the fastest shipping they can consistently deliver. Don't promise 2-day if you can't maintain it. |
| Late Shipment Rate | Medium-High | Percentage of orders shipped after the expected ship date | Keep below 4%. FBA sellers don't worry about this because Amazon handles shipping. FBM sellers must ship on time consistently. One bad week can affect Buy Box eligibility for 30+ days. |
| Seller feedback rating | Medium | Star rating from buyer feedback (not product reviews) | Maintain 95%+ positive feedback. Proactively request feedback removal for reviews that are actually product reviews (not seller feedback). Volume matters too: a seller with 4.8 stars and 1,000 ratings beats one with 5.0 stars and 10 ratings. |
| Inventory depth | Medium | Whether you have enough stock to fulfill orders | Low stock signals to Amazon that you might go out of stock, which means a poor customer experience. Maintain at least 2-4 weeks of inventory at current sales velocity. Amazon is less likely to award the Buy Box to a seller that might run out tomorrow. |
| Time on platform | Low-Medium | Account age and sales history length | Newer sellers face a disadvantage. There's no shortcut here. Consistent strong performance over 3-6 months builds the track record Amazon's algorithm rewards. |
FBA vs. FBM: The Buy Box Reality
Fulfillment by Amazon (FBA) sellers win the Buy Box at a significantly higher rate than Fulfillment by Merchant (FBM) sellers. The reason is straightforward: Amazon controls the customer experience with FBA. It knows the product will be stored, packed, and shipped on time through its own warehouses. That certainty matters to an algorithm designed to protect the customer experience.
This doesn't mean FBM sellers can't win the Buy Box. They can, especially when:
- Their landed price is significantly lower than FBA competitors (enough to offset the fulfillment preference)
- FBA sellers are out of stock
- They use Seller Fulfilled Prime (SFP), which gives FBM sellers a Prime badge and puts them on more equal footing with FBA
- They have exceptional seller metrics (sub-1% ODR, sub-2% late shipment rate, 98%+ positive feedback)
For sellers deciding between FBA and FBM, the Buy Box math often settles the debate. If your product's margins support FBA fees (typically 20-35% of selling price including referral and fulfillment fees), FBA is almost always the better choice for Buy Box competitiveness. If FBA fees make your product unprofitable, consider whether your pricing or cost structure needs adjustment before defaulting to FBM.
Buy Box Monitoring and Strategy
Track your Buy Box percentage
Amazon provides Buy Box percentage in the "Business Reports" section of Seller Central under "Detail Page Sales and Traffic by Child Item." This shows the percentage of page views where your offer was in the Buy Box. If your Buy Box percentage drops below 90% on a product you're the primary seller for, investigate immediately. Common causes: a new competitor with a lower price, a dip in your seller metrics, or an inventory issue flagged by Amazon.
Pricing strategy
Don't race to the bottom. Amazon's Buy Box algorithm doesn't simply award the lowest price. It balances price against the other factors listed above. An FBA seller priced 5% above an FBM seller with mediocre metrics will often still win. Use repricing tools (RepricerExpress, Informed.co, BQool) to automate competitive pricing within a floor you set. Your price floor should be your break-even point after all Amazon fees. Never reprice below profitability just to hold the Buy Box.
Handling Buy Box rotation
When multiple sellers have similar prices and metrics, Amazon rotates the Buy Box among them. You might hold it for 60% of the time and a competitor holds it for 40%. This is normal and expected on competitive ASINs. Your goal is to maximize your rotation share, not necessarily achieve 100%. Rotation share improves when you have a slight edge in any of the algorithm factors (even small metric improvements compound).
Common Buy Box Mistakes
- Undercutting to win at all costs. A race-to-the-bottom pricing strategy might win the Buy Box today but destroys margin. If you're selling at a loss to hold the Buy Box, you're paying Amazon to let you lose money. Set a price floor and stick to it.
- Ignoring seller metrics. Many sellers focus entirely on price and ignore their Order Defect Rate, Late Shipment Rate, and feedback score. A seller with a 2% ODR can lose the Buy Box to a higher-priced competitor with a 0.5% ODR. Check your Account Health dashboard weekly.
- Running out of stock. Stockouts don't just cost you current sales. They cost you Buy Box position that takes days or weeks to recover after you restock. FBA sellers should maintain 30+ days of inventory. Set up inventory alerts at the 14-day mark.
- Not using FBA when margins support it. The Buy Box preference for FBA is strong enough that switching from FBM to FBA, even with the additional fees, often results in a net profit increase because of higher sales volume from increased Buy Box ownership.
Example: Recovering the Buy Box from Unauthorized Sellers
A pet food brand was losing the Buy Box on their top 5 ASINs to three unauthorized resellers who were undercutting their MAP (minimum advertised price) by 8-12%. Buy Box ownership on those listings dropped from 95% to 40%, and sales fell proportionally — 80-90% of Amazon product sales go through the Buy Box, so losing it meant losing the vast majority of revenue on those products. The brand's response: first, they sent cease-and-desist letters through Amazon Brand Registry's Report a Violation tool. Second, they switched from FBM to FBA on all affected ASINs, gaining the fulfillment advantage in the Buy Box algorithm. Third, they worked with their distributor to cut off the source of unauthorized inventory. Within 45 days, Buy Box ownership recovered to 92%, and monthly revenue on those 5 ASINs returned to pre-disruption levels. The lesson: Buy Box defense requires active monitoring and multi-pronged enforcement, not just competitive pricing.
Frequently Asked Questions
Can brand owners always win the Buy Box on their own products?
Not automatically. Amazon treats all eligible sellers equally in the Buy Box algorithm. Brand owners compete on the same factors as resellers. However, brand owners can use Amazon Brand Registry tools and, in some cases, restrict unauthorized sellers through distribution agreements and IP enforcement.
What happens when nobody has the Buy Box?
Amazon sometimes suppresses the Buy Box entirely if it believes no seller's offer provides a good customer value. This usually happens when all sellers' prices are significantly above Amazon's reference price or when all competing sellers have poor metrics. In this case, shoppers see "See All Buying Options" instead of "Add to Cart."
Does advertising affect Buy Box eligibility?
Ad spend doesn't directly influence Buy Box ownership. However, you must own the Buy Box to run Sponsored Products ads on that listing. Losing the Buy Box means your ads stop serving, which means you lose both organic and paid sales simultaneously. This double impact makes Buy Box maintenance critical for any seller running Amazon ads.
The Buy Box is the single most important real estate on Amazon. Losing it means losing 80%+ of your sales on that listing. Winning it consistently requires the right fulfillment strategy, competitive pricing within profitable bounds, and disciplined seller metrics management. Texin.ai helps brands monitor Buy Box status, optimize pricing strategy, and maintain the seller metrics that keep you in the box. Talk to us about your Buy Box strategy.