KPI (Key Performance Indicators)

Amazon & D2C glossary · Harpy Media

A KPI (Key Performance Indicator) is a metric you have deliberately chosen to judge whether the business is winning — not a number that merely exists on a dashboard. On Amazon, the useful KPIs cluster around three questions: is advertising paying for itself, is inventory healthy, and does each unit actually make money?

What is KPI?

A KPI (Key Performance Indicator) is a metric you have deliberately chosen to judge whether the business is winning — not a number that merely exists on a dashboard. On Amazon, the useful KPIs cluster around three questions: is advertising paying for itself, is inventory healthy, and does each unit actually make money?

The discipline matters because dashboards offer hundreds of numbers while attention is finite. A brand that tracks everything tracks nothing. Choosing a handful of indicators — and reviewing them on a fixed rhythm — turns reporting into an early-warning system for margins, stock, and account health.

Why gross revenue is the wrong scoreboard

Revenue is context, not a verdict. A product with high visibility and low conversion is pointing at a listing-content problem; a brand with rising sales and tightening cash flow is being told that fees or bids are eating unit margin. Neither diagnosis is visible if the only number on the wall is top-line sales.

Specific indicators answer specific questions. ROAS tells campaign teams whether the ads are working right now. Sales velocity tells supply chain how much to manufacture. Conversion and traffic metrics separate a listing problem from a demand problem. Strip those out and a brand can scale ad spend on a product that loses money on every order — enthusiastically, and at speed.

Which KPIs matter depends on your fulfilment model

FBA sellers live and die by inventory health. The Inventory Performance Index drives storage limits, so a low score means restrictions and overage fees on top of the fees you already pay; sell-through rate guards against aged inventory quietly absorbing working capital. Both belong on the weekly sheet, not the annual review.

FBM sellers face a different scoreboard: customer-service metrics govern survival. Order Defect Rate, Valid Tracking Rate, and Late Shipment Rate sit against hard thresholds, and dropping through any of them risks suspension or the loss of the Buy Box. The lesson generalises — your fulfilment model dictates which indicators get daily attention, and copying another seller’s dashboard is how you end up monitoring the wrong risk.

In practice

A brand in Home & Kitchen tracks TACoS and unit margin every week. Mid-way through a competitive push the ROAS figure drops and looks alarming — but TACoS holds steady because organic sales have grown underneath the ads. The holistic indicator says keep spending and capture the share; the campaign-only view would have said retreat. The same readout, interpreted correctly, is worth more than a month of guesswork.

How Harpy Media helps

We build KPI sets that ladder up to margin rather than applause. For brands we work with, TACoS has come down 40% in 60 days and conversion has risen 28% on the same traffic — both outcomes of diagnosing the right indicator and acting on it, not of watching every number at once.

KPI FAQ

What are the most important Amazon KPIs?

For most brands: TACoS, contribution margin or profit per unit, the Inventory Performance Index, conversion rate, and Order Defect Rate. Together they cover advertising efficiency, unit economics, inventory health, and the account-health floor you cannot afford to fall through.

How does TACoS differ from ACoS?

ACoS measures ad spend against the sales the ads directly generated. TACoS measures all ad spend against total revenue, including organic sales — which shows whether advertising is growing the whole business, not just paying for its own clicks.

What happens if my Order Defect Rate is too high?

Amazon requires sellers to keep ODR below 1%. If it climbs above that threshold through negative feedback, A-to-z Guarantee claims, or chargebacks, the account can be restricted or suspended — which is why ODR sits on the daily sheet, not the quarterly one.