Overview

A recent conversation with veteran Amazon merchant Minoru Isisola from Spain underscored that the health of an Amazon store hinges on a handful of profitability ratios rather than raw sales numbers. Sellers who track these indicators can spot hidden costs early, allocate ad spend wisely, and scale with confidence.

Key Points

• Gross Margin — Reveals the amount left after subtracting product cost and Amazon’s referral fees; for a €45 kitchen tool with €15 production cost and a €6 fee, the margin stands at €24 per unit.
• Net Profit Margin — Captures the true bottom‑line after all operating expenses such as PPC, fulfillment, and storage are deducted; the same tool would net €16 once €5 advertising and €3 fulfillment fees are accounted for.
• Return on Advertising Spend (ROAS) — Indicates how many euros of revenue each advertising euro generates; €10,000 in sales from €2,000 of ad spend translates to a 5× ROAS.
• Advertising Cost of Sale (ACoS) — Expresses ad spend as a percentage of attributed sales; the €2,000 spend on €10,000 sales yields an ACoS of 20 %, a benchmark for campaign efficiency.
• Inventory Turnover Ratio — Measures how many times inventory is sold and replenished in a year; €150,000 of yearly COGS against an average €30,000 stock value results in a turnover of 5, meaning the inventory cycles five times annually.
• Break‑Even Point — Calculates the sales volume required to cover all fixed and variable costs; with €20,000 in fixed overhead and a €12 contribution margin per unit, roughly 1,667 units must be sold to break even.

How Profitability Metrics Work

1. Compute Gross Margin — Subtract the cost of goods sold and Amazon’s referral charge from the list price; a €45 gadget with €15 manufacturing cost and a €6 fee leaves €24 gross profit per unit.
2. Derive Net Profit — From the gross profit, deduct every additional expense such as pay‑per‑click advertising, FBA fulfillment fees, and monthly storage costs; applying €5 PPC and €3 fulfillment to the gadget reduces net profit to €16 per unit.