YoY

 YoY is one of Amazon’s most widely used growth indicators. It helps vendors, sellers, and Amazon teams evaluate long-term trends while adjusting for seasonality (e.g., comparing Q4 holiday sales this year vs. last year).

How It Works:

• Formula:
• Example: If July 2025 sales = $120,000 and July 2024 sales = $100,000 → YoY growth = +20%.
• Common use cases:
  • Sales revenue and units sold.
  • Advertising efficiency (ACOS, ROAS).
  • Traffic, conversion, and Buy Box % changes.
  • Inventory health (instock %, WOC/DOI trends).

Benefits for Vendors:

• Seasonality control: Compares like-for-like periods (e.g., holiday vs holiday).
• Performance benchmarking: Shows if strategies are working over time.
• Negotiation leverage: Vendors can use positive YoY growth in AVN discussions.

Benefits for Amazon:

• Category management: Tracks category and brand growth trends.
• Forecasting: Helps identify long-term demand shifts.
• Operational alignment: Ensures vendors scale in line with Amazon’s growth expectations.

Challenges:

• Sensitive to external factors (e.g., inflation, macroeconomic shifts, pandemic effects).
• One-time events in the prior year (e.g., a massive Prime Day promotion) may skew comparisons.
• Should be combined with shorter-term KPIs (WoW, MoM) for a complete view.

Why It Matters:
YoY analysis is a standard growth benchmark for both vendors and Amazon. It shows whether a brand is truly expanding in sales, efficiency, and market share year after year.

Example:
A beauty brand reports +35% YoY growth in Q4 2025 vs Q4 2024, largely driven by expanded participation in Black Friday and increased Sponsored Brands ad spend.

In short:
YoY (Year over Year) measures performance changes compared to the same period in the prior year, helping vendors and Amazon track long-term growth while accounting for seasonality.