Eva Answers / Working with an agency
What KPIs Should I Track If I Hire a Full-Service Amazon Agency?
Answered by Hai Mag, Founder & CEO, Eva Commerce, with 20+ years in eCommerce transformation, marketplace optimization, and AI-driven automation.
Last reviewed: October 26, 2026
Short answer: Track a short list tied to profit, not just ad efficiency: total sales and units, ACOS and ROAS, ad spend as a share of total sales, conversion rate, search performance on your priority keywords, in-stock status, account health and contribution profit by SKU. Agree a dated baseline and a monthly reporting cadence before the agency starts, and judge results against that baseline over a full quarter. ACOS alone can look good while total sales or profit fall.
The KPIs to agree on, and where they come from
| KPI | What it tells you | Where the data comes from |
|---|---|---|
| Total sales and units | Whether the account is growing overall, not just through ads | Seller Central sales reports |
| ACOS and ROAS | How efficiently ad spend turns into ad-attributed sales (ACOS = ad spend / ad sales x 100; ROAS = ad sales / ad spend) | Amazon Ads console |
| Ad spend as a share of total sales | Whether advertising is lifting the whole business or just buying sales; ask the agency to show the formula it uses | Ads spend plus Seller Central total sales |
| Conversion rate and click-through rate | Whether listings and ads persuade shoppers | Amazon Ads and Seller Central reports |
| Search performance on priority keywords | Impressions, clicks, cart adds and purchases for the searches that matter to your brand | Search Query Performance in Brand Analytics (needs Brand Registry and a Professional account) |
| Inventory and in-stock status | Whether growth is being held back or wasted by stockouts or overstock | Seller Central inventory reports |
| Account health | Whether policy or performance issues put listings at risk | Account Health dashboard in Seller Central |
| Contribution profit by SKU | Whether the growth is profitable after fees, ads and product cost | Your financial data combined with Amazon fees and ad spend |
How to set this up with a new agency
- Record a dated baseline. Before work starts, capture sales, advertising cost, conversion, inventory and contribution profit for the same period, so later results have something to compare against.
- Agree scope and ownership. Write down the products, markets, constraints, who owns each task and how often you get reports.
- Set targets from your margins. Work out break-even ACOS per product from your profit margin, then set targets by goal, such as launch, growth or profit.
- Review monthly, judge on trends. Look at the same KPIs every month and compare them with the baseline over a full quarter rather than week to week.
- Ask for the why. A good report explains what changed, why, and what the agency will do next, not just the numbers.
Exceptions
- Launch periods. New products often need higher ad spend to build ranking and reviews, so ACOS can sit above target for a while by design.
- Brands without Brand Registry. Brand Analytics, including Search Query Performance, is only available to Brand Representatives of brands enrolled in Brand Registry.
- Seasonal businesses. Compare peak months with the same period last year, not with the month before.
- Vendor Central brands. Reporting and data access differ from Seller Central, so agree on the equivalent reports up front.
In Eva’s full-service Amazon management, each engagement starts by agreeing products, markets, constraints, ownership and reporting cadence, and progress is measured against a dated baseline for sales, advertising cost, conversion, inventory and contribution profit. Every engagement includes a dedicated Amazon Senior Growth Specialist working in your account about 30 to 35 hours a month and monthly performance reports, following a 6-month roadmap: foundation (days 0 to 30), acceleration (days 31 to 90) and scale (days 91 to 180).
Follow-up questions
Is ACOS enough to judge an Amazon agency?
No. Amazon Ads calls ACOS just one KPI and recommends also looking at impressions, conversion rate, click-through rate and return on investment. ACOS only covers ad-attributed sales, so pair it with total sales and profit.
What is a good ACOS?
Amazon Ads says there is no definitive number. To stay profitable your ACOS needs to be below your profit margin, which is your break-even ACOS; a launch or awareness goal can justify running closer to it for a period.
Who should own the Amazon data and reports?
You should. Keep Seller Central, the Amazon Ads account and Brand Registry in your company’s name and give the agency user access, so the history stays with you if you change agencies.