The Complete Amazon Seller Analytics Guide

Five numbers carry most of the signal: ACoS (campaign ad efficiency), TACoS (how dependent the whole account is on ads), true profit per unit (after referral and FBA fees), sales velocity (units per day), and inventory runway (days of stock left). Revenue and sessions are context; these five drive decisions.

ACoS is ad spend over ad-attributed revenue — use it for campaigns. TACoS is ad spend over total revenue, organic included — use it for the account trend. Healthy growth looks like steady ACoS with a slowly falling TACoS as organic rank builds; a rising TACoS with flat sales means ads are just renting revenue.

Amazon's referral fee (~15% in most categories) and FBA fulfilment fee can take 25–40% of the sale price before product cost or ads. Calculate net profit per unit — sale price minus product cost, referral, FBA and other costs — for every SKU, because a strong seller on revenue can be a weak one on profit once fees are in.

Stockouts cost you sales and rank, and rank is slow to rebuild. Track sales velocity (units per day, adjusted for growth) and inventory runway (units ÷ daily sales), and reorder when runway hits your lead time plus a safety buffer. On Amazon, running out is often more expensive than over-ordering.

Daily: sales, units, the ACoS/TACoS trend, and any Buy Box or stock alerts. Weekly: profit per unit by SKU, TACoS trend, inventory runway on top products, and organic vs ad share of sales. Roll them onto one board so the check takes minutes, not a morning of downloading reports.

Amazon is one channel. To see the real picture, put Amazon sales and profit next to Shopify, your ad spend across Meta and Google, and blended ROAS — so decisions are made on the whole business, not one marketplace in isolation.