2. Sales by Product/SKU
Identifying which specific products are driving growth or decline, rather than looking only at account-wide totals.
3. Conversion Rate
The percentage of listing visitors who actually purchase — a declining conversion rate often signals a listing or pricing issue before sales numbers fully reflect it.
Advertising KPIs
4. ACoS (Advertising Cost of Sale)
Tracked against your calculated breakeven ACoS, both account-wide and at the campaign level.
5. TACoS (Total Advertising Cost of Sale)
Your total ad spend against total sales, showing advertising's overall contribution and trend over time.
6. Click-Through Rate (CTR)
How often your ads are clicked relative to impressions — low CTR despite good impressions often points to a listing or creative issue.
7. Wasted Ad Spend
Spend on search terms that generated clicks but no conversions — a direct indicator of negative keyword gaps.
Inventory KPIs
8. Stockout Rate
How often listings go out of stock — even brief stockouts can meaningfully hurt organic ranking recovery time.
9. Inventory Turnover
How quickly stock is selling relative to what's on hand, helping catch both overstock and understock risks early.
10. Long-Term Storage Exposure
Inventory at risk of triggering long-term storage fees, which quietly erode margin if left unaddressed.
Account Health KPIs
11. Order Defect Rate (ODR)
The percentage of orders with negative feedback, claims, or chargebacks — a core account health metric.
12. Late Shipment Rate
Directly affects account standing and, on some platforms, future order allocation.
13. Return Rate
High return rates hurt both account health and profitability, and often point to listing accuracy issues.
How to Prioritize These KPIs Month to Month
- Always review: Total sales, ACoS/TACoS, and account health metrics — these are your core monthly checkpoint
- Review when something looks off: SKU-level sales, CTR, and inventory turnover — useful for diagnosing a specific issue flagged by the core metrics
- Review before major decisions: Long-term storage exposure before placing new orders; return rate trends before scaling advertising further
Building a Simple Monthly KPI Dashboard
- Pull the core metrics (sales, ACoS/TACoS, ODR, late shipment rate) into one consolidated view each month
- Compare against the previous month and the same month last year to account for seasonality
- Flag any metric moving in the wrong direction for deeper investigation, even if it hasn't crossed a critical threshold yet
- Document the "why" behind significant changes, not just the numbers themselves
Red Flags in How an Agency Reports These KPIs
- Reports that only show sales totals without ACoS, account health, or inventory context
- No comparison against previous periods, making it hard to judge whether things are actually improving
- Vague explanations for metric changes, without specific actions taken in response
Getting Started
KPI Baseline Review (Week 1)
- Pull your current numbers across these core KPI categories
- Identify which metrics are trending in the wrong direction
- Build a simple monthly tracking process going forward
Conclusion
Not every metric on your dashboard deserves equal attention — focusing on sales, advertising efficiency, inventory health, and account health each month gives you the clearest, most actionable picture of how your account is actually performing.
Want a KPI review of your current account? Contact us for a free performance audit.
Key Takeaways
- Track sales growth and SKU-level performance to identify your best-selling products.
- Monitor ACoS and TACoS to maintain profitable advertising spend across all campaigns.
- Prevent revenue loss by minimizing stockout rates and optimizing inventory turnover cycles.
- Maintain high account health scores by keeping order defect and return rates low.
- Establish a monthly reporting dashboard to spot performance red flags early.
FAQ
What is the difference between ACoS and TACoS?
ACoS measures the efficiency of your specific ad campaigns relative to the revenue generated by those ads. In contrast, TACoS measures your total advertising spend against your overall sales. While ACoS helps optimize individual campaigns, TACoS provides a broader view of how advertising influences your business's total profitability and market growth.
Why is the inventory turnover rate important for marketplaces?
Inventory turnover rate indicates how quickly you sell and replace your stock over a specific period. High turnover suggests strong demand and effective replenishment, while low turnover signals stagnant capital and potential storage fees. Monitoring this metric ensures you avoid excess stock while keeping your best-selling items available for customers.
How often should I review my marketplace KPIs?
You should perform a comprehensive review of your KPIs on a monthly basis. This cadence allows you to identify trends, address performance dips before they escalate, and make data-driven adjustments to your advertising or inventory strategy. However, critical metrics like account health should be monitored more frequently to prevent suspension risks.
What are the common red flags in agency KPI reporting?
Red flags include agencies focusing only on vanity metrics like impressions while ignoring profit-based KPIs like TACoS. Avoid agencies that provide inconsistent reports, lack transparency regarding wasted ad spend, or fail to explain the relationship between your inventory levels and sales performance. Always demand clear, actionable insights rather than just raw data.
