Definition
Every eBay sale flows through one gate: Best Match. When a buyer searches for an item, eBay's algorithm scores every competing listing and surfaces one winner in the primary "Buy It Now" position — that's the Buy Box. Price is the single lever sellers control most directly. But slashing price without a limit destroys margin. The sellers who consistently win the Buy Box are the ones who reprice to the edge of competition, then hold there — protected by a hard floor below which they will never go.
eBay's Buy Box is the prominent 'Buy It Now' button that appears when multiple sellers list the same or equivalent item. Unlike Amazon's buy box — which rotates among sellers sharing a single product page — eBay's version is tied to Best Match, the ranking algorithm that decides which listing a shopper sees first in search results. Winning Best Match is effectively winning the Buy Box: your listing loads first, converts at a higher rate, and generates the bulk of sales volume for that search query.
eBay evaluates total buyer cost — item price plus shipping — not item price alone. A seller charging $18.00 with free shipping outranks a seller charging $14.99 plus $5.00 shipping in Best Match scoring, because the buyer's total is lower. This means your repricing strategy must account for your shipping model before setting a floor. eBay also looks at recent sales velocity: a listing that has converted well at a price point carries historical credibility that helps it hold rank even when a new competitor undercuts by a few cents.
Repricing to win Best Match without a floor is how sellers accidentally sell below cost. Here is a concrete floor calculation for a mid-range electronics accessory. Suppose your landed cost (cost of goods) is $8.00, you offer free shipping that costs you $4.00 to fulfill, eBay's final value fee is 13.25% of the total sale price, and you require a minimum 15% net margin on cost. Your floor calculation works as follows: you need the sale price P to satisfy P minus (0.1325 × P) minus $4.00 minus $8.00 >= 0.15 × $8.00. Solving: 0.8675P >= $13.20, so P >= $15.22. Round up to $15.25 as your hard floor. Undercut will reprice down to $15.25 and stop — it will never go lower, no matter how aggressively a competitor drops.
A competitor can change their price at any hour. Manual repricing — checking listings once a day or once a week — means you spend most of your time out of position. Undercut's Pro and Scale plans both reprice every 15 minutes (Scale adds capacity for up to 10,000 listings plus priority support, not faster repricing). For high-competition categories like consumer electronics or media, that frequency is the difference between holding the top spot through a busy weekend or watching a competitor absorb your sales. The per-listing AI aggressiveness tuning on the Pro and Scale plans lets you control how quickly each listing closes on a competitor's price versus how much cushion it keeps — so you are not always racing to the exact floor.
The most common mistake sellers make when they start repricing is treating it as a pure race to the bottom. The Buy Box rewards competitiveness, but eBay's algorithm also depresses search visibility for listings with very low sell-through rates — a sign of a listing that is priced so low it attracts returns, disputes, or low-quality buyers. A hard floor is not just a financial safeguard; it is also a signal that you are pricing your item appropriately for its condition and your fulfillment model. Undercut enforces a per-listing floor you set, ensures every automated price move stays above that threshold, and logs every reprice so you can audit what happened and when.
Start free with 25 listings. No credit card needed. Set your hard floor on day one and let Undercut handle the rest.
Start freeDoes eBay have a Buy Box the same way Amazon does?
Not exactly. Amazon's buy box rotates among sellers sharing one product page. eBay's equivalent is the top Best Match position in search results, which is determined per listing rather than per product catalog entry. Winning it means your individual listing outscores competing listings on price, seller metrics, and listing quality.
Will repricing to the lowest price always win Best Match?
Price is the strongest lever, but not the only one. A seller with a 99.8% feedback score, one-day handling, and a well-optimized listing title can hold Best Match against a slightly lower-priced competitor with poor seller metrics. Focus on being price-competitive within your floor, and keep your service metrics strong.
How do I calculate the right floor so I never sell below cost on eBay?
Add your cost of goods plus shipping plus eBay's final value fee percentage (typically 12.9%–15% depending on category) plus any minimum margin you require. That sum is your floor. For example, a $8.00 item with $4.00 shipping, 13.25% fees, and a 15% margin target yields a floor of approximately $15.25. Set that number in Undercut per listing and the repricer will never drop below it.
How often does eBay Best Match re-rank listings?
eBay re-evaluates Best Match rankings continuously as buyer searches happen, but the impact of a price change propagates within minutes to a few hours. Undercut's Pro and Scale plans both reprice every 15 minutes, which is fast enough to respond to competitor moves before you lose meaningful traffic.
Can I use a single floor for all my eBay listings?
You set a floor on each listing, and a single blanket number across all of them is usually too blunt. A $15 item in the Books category carries different fee rates and shipping costs than a $15 item in Electronics. Undercut supports per-listing floors so each SKU reflects its actual cost structure.
Related: How to Win the eBay Buy Box · How to Avoid Selling Below Cost on eBay · What Is a Price Floor? · What Is Repricing? · Repricing Without Losing Margin