Quick answer: The most important Amazon seller KPIs are units ordered, ordered product sales, sessions, unit session percentage, Featured Offer percentage, sales velocity, days of inventory, return rate, ad spend, ACOS, TACOS, and contribution profit. No single KPI describes the health of an Amazon business on its own.
Amazon gives sellers more numbers than most people can use. The problem isn't access to data. It's knowing which number answers which question.
A sales figure tells you what happened. It doesn't tell you whether traffic fell, conversion weakened, another offer won the Featured Offer, advertising became expensive, or inventory ran out. That diagnosis requires a small group of metrics read together.
The short list for a daily dashboard
A seller doesn't need all 30 metrics every morning. Start with these:
| Question | Metric to check first | Metric to check beside it |
|---|---|---|
| Are sales moving? | Units ordered and sales | Prior-period comparison |
| Is traffic changing? | Sessions | Ad impressions and clicks |
| Is the page converting? | Unit session percentage | Featured Offer percentage |
| Are we winning the offer? | Featured Offer percentage | Price and delivery promise |
| Will we run out? | Days of inventory | Sales velocity and inbound stock |
| Are ads efficient? | ACOS | TACOS and margin |
| Are returns damaging the SKU? | Return rate | Return reason and disposition |
| Is the account operationally safe? | Account Health Rating | ODR, late shipment, and cancellation rate |
Sales and demand metrics
Units ordered is the number of product units customers ordered during the selected period. Units and orders aren't the same, one order can contain several units. Use it for demand and inventory planning, not as a profit measure.
Total order items is the number of distinct order lines. If a customer buys three units of the same SKU in one order line, units ordered can be three while total order items is one, useful when pack quantity matters.
Ordered product sales is the selling value associated with ordered products during the reporting period. Depending on the report, taxes, shipping, discounts, cancellations, and refunds may be treated differently, which is why this figure may not match a payment or settlement report.
Sales velocity equals units sold during a period divided by the number of days in the period. A product selling 90 units in 30 days has a calendar-day velocity of 3 units a day, a formula covered further in Amazon sales velocity.
Average selling price equals ordered product sales divided by units ordered. It helps identify discounting and product-mix shifts, and can fall even when no individual price changed if customers bought more lower-priced products.
Traffic and conversion metrics
Sessions represent a customer visit to an Amazon detail page. Sessions belong to the detail page, not exclusively to your offer on a shared ASIN, so read them beside Featured Offer percentage when several sellers share the listing.
Unit session percentage equals units ordered divided by sessions, times 100. If 20 sessions produce 4 units, unit session percentage is 20%. It's often described as Amazon's conversion rate, but it's unit-based, a shopper buying several units can lift the percentage above order conversion.
Featured Offer percentage is the percentage of eligible detail-page views during which your offer appeared as the Featured Offer, still commonly called Buy Box percentage. A conversion decline with stable Featured Offer share suggests a page, price, or demand problem. A sales decline with falling Featured Offer share suggests an offer-ownership problem, the distinction covered in Amazon conversion rate by ASIN.
Advertising metrics
Click-through rate equals clicks divided by impressions, times 100, reflecting relevance, main image, price, and placement. Cost per click equals ad spend divided by clicks. Advertising cost of sales (ACOS) equals ad spend divided by ad-attributed sales, times 100. Return on ad spend (ROAS) equals ad-attributed sales divided by ad spend, the inverse presentation of ACOS. Total advertising cost of sales (TACOS) equals ad spend divided by total sales, times 100, a seller-created metric rather than a standard Amazon Ads term. All four are covered in depth in TACOS vs ACOS vs ROAS.
Inventory metrics
Available inventory is FBA units currently available to ship to customers, distinct from total units Amazon physically holds. Reserved inventory is temporarily unavailable because units may be tied to customer orders, fulfillment-center transfers, or processing. Inbound inventory is units in an inbound workflow. Unfulfillable inventory is at Amazon but not currently sellable. Stranded inventory doesn't have an active buyable offer. All five statuses are broken down in Amazon FBA inventory statuses explained.
Days of inventory equals usable inventory divided by daily sales velocity. If 120 sellable units are available and the product sells 4 units a day, it has about 30 days of inventory, a calculation covered fully in days of inventory for Amazon sellers. Inventory age is the length of time FBA units have been stored, and matters because older units can trigger escalating storage costs and aged-inventory surcharges.
Returns and customer-experience metrics
Return rate equals returned units divided by sold units for a comparable cohort or period. A raw return count is misleading: ten returns from 1,000 units is very different from ten returns from 50 units, covered further in Amazon return rate by ASIN. Refund rate and return rate aren't always identical, a refund can occur without a physical return.
Account and fulfillment metrics still matter
An analytics dashboard shouldn't distract from metrics tied to selling privileges. Seller Central's Account Health area may include Account Health Rating, Order Defect Rate, late shipment rate, pre-fulfillment cancellation rate, and valid tracking rate, depending on marketplace and fulfillment method. Definitions and thresholds change, so use Seller Central's current Account Health guidance rather than an old blog post.
A diagnostic sequence, not a wall of numbers
A seller's sales dashboard falls 18% in a week. The instinct is to blame advertising and raise bids, which makes the problem more expensive. The better sequence: sessions are almost flat, unit session percentage slipped only slightly, but Featured Offer percentage dropped from 86% to 61% on three high-volume ASINs after delivery dates slowed once FBA stock moved into reserved and transfer statuses. Ad clicks continued, but another seller captured more of the purchases. The glossary doesn't solve the problem by itself. It helps ask the right second question.
EcomSanity brings together sales velocity, FBA stock, days of inventory, Featured Offer percentage, conversion, returns, aged-stock risk, and category sales in one operating view, not a replacement for settlement accounting, Account Health, or keyword research, but a way to see which metric moved first. For which Seller Central report actually supplies each of these numbers, see the Amazon Seller Central reports guide.
Frequently asked questions
What are the five most important Amazon KPIs?
For a compact operating view, track units ordered, sessions, unit session percentage, Featured Offer percentage, and days of inventory. Add ACOS or TACOS when advertising is material, and return rate when product quality or fit is a risk.
What is a good Amazon conversion rate?
There's no universal good rate. Category, price, traffic, delivery promise, and shared-ASIN competition all matter. Compare each ASIN with its own history and similar products rather than an industry-wide number.
Should Amazon sellers track revenue or profit?
Both. Revenue measures demand and scale; profit measures economic value after fees, advertising, returns, inbound freight, and cost of goods. Tracking only one hides the other half of the story.