Buy Box %
How often the Add to Cart button on your listing was yours.
What it means
Buy Box % is the share of your selected date range where your offer owned the Add to Cart button on a listing. Several sellers can share one Amazon listing, but only one holds that button at a time. It's averaged across the days in range rather than a snapshot, so 90% can be 3 lost days out of 30 or a shaky grip on all 30 — and those need different fixes.
Show the math
Formula and a worked example
Buy Box ownership is measured per SKU per day — the share of that day your offer held the Add to Cart button.
Across days in the selected range means the figure on screen is the average of those daily numbers over whatever dates you picked. Change the range and the number changes.
Worked example. Over 30 days a SKU holds the Buy Box on 27 days and loses it completely on 3. The average is 27 ÷ 30 = 90%. If that SKU sells €10,000 a month, those 3 days are roughly €1,000 of sales that went to another seller — while your ads kept paying for clicks on all 30.
Pick the 7 days that contain those 3 and the same SKU shows 57%. Pick the quarter and it shows 97%. One event, three different-looking numbers. Widen the range to judge the SKU, narrow it to find the day it broke.
It answers the question
Is this SKU's problem demand at all, or shoppers arriving at a listing where someone else takes the order? Anything under 100% means that for part of the range, shoppers landing on your listing could buy from another seller instead.
Why it matters
Everything else on Amazon assumes you own the Buy Box. Your ads point at the listing and your price sits on it, so losing it means the traffic still arrives while the order goes elsewhere — you're a shop where the customer walks in and someone else is standing behind your till.
It's also the quietest way to lose money. Nothing errors, no campaign changes, no alert fires: sales for that SKU fall, ACOSACOSThe share of ad revenue eaten by the ads themselves.Under 20% is healthy on it climbs, and the ad account looks exactly the same as last week.
What good looks like
There's no published standard for Buy Box % and the app doesn't grade it, because the same number means different things on different listings. Where you're the only seller it sits near 100% and tells you nothing; on a listing three sellers contest, 85% can be excellent.
So judge it against yourself first: a SKU that ran at 96% for months and now runs at 78% is missing about 1 day in 4, and that change is the signal rather than the level. Watch the SKUs you advertise most closely, because every point below 100% is a slice of budget landing on a page where the button isn't yours. Sort the SKU Performance table by Buy Box % ascending and read the top 10 rows — worth doing weekly.
How to improve it
| Lever | What you do | Expect | How long | Watch out for |
|---|---|---|---|---|
| Fast Match the winning offer's landed price | Compare your price plus shipping against the offer holding the box, and close the gap on the SKUs that earn | Buy Box % recovers within a day or two | 1–3 days | Every point of price comes out of margin. You can win the box back and lose money on every unit that sells through it. |
| Fast Clear the stockouts | Raise reorder points on the SKUs whose Buy Box % dipped on the days stock hit zero | No more zero days in the daily view | 1–2 weeks | More cash tied up in inventory, plus storage fees on anything that turns slowly. |
| Slow Move the SKU to FBA | Ship your fast sellers into Amazon so the delivery promise stops counting against you | Higher share at the same price | 4–8 weeks | FBA fees eat unit margin, and inbound shipments mean weeks where nothing improves at all. |
| Slow Repair your seller metrics | Work down late shipments, cancellations and defects — the scores that decide whether you're eligible at all | Better share across the whole catalogue, not one SKU | 1 quarter | The scores are rolling averages, so nothing moves for weeks. Tightening delivery promises to fix them costs shipping money. |
Every lever costs something somewhere. The last column is the one to read twice.
Read it with
Buy Box % on its own tells you the door was blocked. Next to Sales on the same row, it tells you whether that's why the SKU is down.
Working as intended
You own the button and the SKU is growing. The one thing to confirm is that you didn't buy the box back with a price cut worth more than the sales it brought.
Growing with a leak
Demand is covering for a problem: the SKU is up, but part of the month it sold for somebody else. Fix it and you keep the growth and recover the missing days.
Not a Buy Box problem
You owned the button all month and sales still fell. Stop looking here — this is demand, pricing, seasonality, or a listing that stopped converting.
The silent killer
Sales fell because shoppers couldn't buy from you. It's usually a stockout or a price change — yours or theirs. Fix the cause before you touch a single bid.
Read together they tell you whether to fix the campaign or the offer. An ACOS spike with no campaign change is a Buy Box story: the ads keep buying clicks at the same price and those clicks stop converting, because the button belongs to someone else. An ACOS spike with Buy Box % steady is the campaign's own doing.
Buy Box % is one listing and TACOS is the whole account, so together they size how far a listing problem has spread. Several top SKUs losing the Buy Box in one week drags Total Sales down while Ad Spend holds, so TACOS climbs and the ad account looks broken when the problem was never in it. Buy Box % alone can't show the damage; TACOS alone can't show the cause.
Common misreads
It's an average. 90% across 30 days can hide 3 days at zero, and those are the days your ads spent money on a competitor's sale. Narrow the date range a week at a time and find them.
Price is one input among several. Running out of stock loses it outright, and so can a slower delivery promise or a slipping seller score. Check stock and shipping before you cut price — a cut you didn't need costs margin on every unit from then on.
Usually that means nobody else sells the listing. It says nothing about whether anyone bought, so read 100% as no blocker here and judge the SKU on its sales.
Also called
Buy Box win rate · Featured Offer % · Buy Box share · buy box ownership
See yoursYour Buy Box % for every SKU — sort it lowest first and the leaks are at the top.
Open SKU Performance →