The Herfindahl-Hirschman Index (HHI) is the gold standard for measuring market concentration in economics, used by the U.S. Department of Justice and the Federal Trade Commission to evaluate merger impacts. In Amazon analyse de niche, HHI provides an objective, numerical answer to one of the most important questions a vendeur can ask: how concentrated is this market, and is there room for a new entrant?
Unlike subjective assessments of concurrence ("this looks competitive" or "there seem to be a lot of vendeurs"), HHI reduces market structure to a single number that can be consistently compared across niches, catégories, and places de marché.
The HHI Formula
Herfindahl-Hirschman Index
Where S = part de marché of each vendeur (as a whole number, not decimal)
Each vendeur's part de marché is expressed as a percentage (e.g., 25 for 25%, not 0.25), squared, and then all squared values are summed. The result ranges from near 0 (perfectly competitive, infinite vendeurs with equal shares) to 10,000 (monopoly, one vendeur with 100% share).
Understanding the Scale
The DOJ defines three concentration zones:
- HHI below 1,500: Unconcentrated (competitive) market. Multiple vendeurs compete actively, no single player dominates, and new entrants face manageable barriers.
- HHI 1,500 to 2,500: Moderately concentrated market. A few vendeurs hold significant share, but the market is not locked down. Entry is possible with differentiation.
- HHI above 2,500: Highly concentrated market. One or a few vendeurs dominate. Entry requires significant investment and carries high failure risk.
For Amazon analyse de niche specifically, we refine these thresholds based on observed outcomes across thousands of lancement de produites. The profitable niche criteria recommend an ideal HHI range of 800-1,500 for new product entry.
How to Calculer HHI for an Amazon Niche
Step 1: Define the Niche Boundary
HHI calculation requires a clearly defined market. On Amazon, this means identifying the specific search term that defines your competitive set. "Yoga mats" and "extra thick yoga mats" are different niches with different HHI values. Use the primary keyword you would target for campagnes PPC as the niche boundary.
Step 2: Estimate Revenus Mensuels for Top Sellers
For the top 20-30 vendeurs appearing on pages 1-2 of the search results for your primary keyword, estimate revenus mensuels. Methods include:
- BSR-based estimation: Amazon's Best Sellers Rank (BSR) correlates with daily unit sales. Tools like Jungle Scout, Helium 10, and Keepa provide BSR-to-sales conversion models. Multiply estimated daily units by price to get revenus mensuels.
- Brand Analytics (for registered vendeurs): Provides click share and conversion share data that can be used to estimate relative revenus distribution.
- Manual tracking: Monitor inventaire levels over 7-14 days using the "add 999 to cart" method (less reliable for FBA vendeurs with large inventories, but useful for triangulation).
Step 3: Calculer Market Shares
Convert estimated revenus to part de marché percentages. Total market revenus = sum of all tracked vendeurs' revenus. Each vendeur's share = (vendeur revenus / total revenus) x 100.
Step 4: Square and Sum
Square each part de marché value and sum all squared values. This is the HHI.
Worked Example: Bamboo Cutting Boards
Let us calculate HHI for the "bamboo cutting board" niche sur Amazon US:
| Seller | Est. Revenus Mensuels | Market Share | Share Squared |
|---|---|---|---|
| Brand A | $85,000 | 22.4% | 501.8 |
| Brand B | $62,000 | 16.3% | 265.7 |
| Brand C | $41,000 | 10.8% | 116.6 |
| Brand D | $38,000 | 10.0% | 100.0 |
| Brand E | $29,000 | 7.6% | 57.8 |
| Brand F | $22,000 | 5.8% | 33.6 |
| Brand G | $18,000 | 4.7% | 22.1 |
| Brand H | $15,000 | 3.9% | 15.2 |
| Brands I-R (10) | $70,000 | 18.4% combined | ~43.0 |
| Total | $380,000 | 100% | 1,155.8 |
HHI = 1,156. This falls in the unconcentrated zone, indicating a competitive market structure that is accessible to new entrants. The leading marque holds 22.4% share -- significant but not dominant -- and revenus is distributed across multiple players. This is a healthy competitive environment for a new entrant with a differentiated product.
Worked Example: Instant Pot Accessories
Compare with the "instant pot accessories" niche:
| Seller | Est. Revenus Mensuels | Market Share | Share Squared |
|---|---|---|---|
| Brand A | $210,000 | 38.2% | 1,459.2 |
| Brand B | $125,000 | 22.7% | 515.3 |
| Brand C | $78,000 | 14.2% | 201.6 |
| Brand D | $52,000 | 9.5% | 90.3 |
| Brand E | $35,000 | 6.4% | 41.0 |
| Brands F-P (11) | $50,000 | 9.1% combined | ~12.0 |
| Total | $550,000 | 100% | 2,319.4 |
HHI = 2,319. This falls in the moderately concentrated zone, approaching the highly concentrated threshold. Two marques control 61% of the market. While entry is not impossible, it would require significant differentiation and PPC investment to capture even 5% part de marché. The risk-reward ratio is less favorable than the bamboo cutting board example.
HHI Limitations and Adjustments for Amazon
While HHI is powerful, applying it to Amazon niches requires understanding its limitations:
Limitation 1: Estimation des Revenus Accuracy
HHI quality depends entirely on the accuracy of revenus estimates. BSR-based tools have error margins of 20-40%, which propagates into the HHI calculation. To mitigate this, track BSR data over 30+ days rather than relying on point-in-time snapshots. The longer the observation period, the more accurate the revenus estimates.
Limitation 2: Niche Boundary Definition
The calculated HHI changes significantly depending on how broadly or narrowly you define the niche. "Cutting boards" will produce a lower HHI than "bamboo cutting boards with juice grooves" because the broader definition includes more vendeurs. Always use the search term that matches your intended PPC targeting for consistency.
Limitation 3: Variation Listings
Amazon parent-child variation listings (multiple sizes/colors under one ASIN) aggregate reviews and sales data. A vendeur with 5 variations appears as one entity in HHI calculations but actually covers multiple market segments. Adjust by separating variation-level revenus when possible.
The RIDGE Adjusted HHI
In our analyse de niche reports, we calculate an adjusted HHI that accounts for these limitations by using 30-day rolling BSR data, normalizing for variation listings, and weighting recent sales more heavily than historical data. This produces a more actionable concentration metric than raw HHI calculations.
Get Precise HHI Analysis for Your Niche
RIDGE calculates adjusted HHI using 30-day rolling BSR data and proprietary revenus estimation models, providing a more accurate concentration metric than point-in-time snapshots.
Order Concentration AnalysisUsing HHI in Decision Making
HHI should never be used in isolation. It is one component of a comprehensive niche evaluation that includes demande validation, profitability modeling, and évaluation des risques. Here is how to integrate HHI into your decision framework:
- Calculer HHI as part of concurrence assessment -- Step 2 of the 7-step validation framework.
- Cross-reference with other saturation signals -- Average review counts, CPC levels, marque concentration, and margin trends as described in our 5 saturation signals guide.
- Compare across places de marché -- The same niche may have an HHI of 2,800 in the US but 1,200 in Allemagne. This place de marché-level comparison can redirect your entry strategy to a less concentrated geography.
- Track over time -- Rising HHI indicates increasing concentration (consolidation). Declining HHI suggests new entrants are successfully capturing share (opportunity window). Monitor quarterly.
The most profitable lancement de produites consistently target niches with HHI in the 800-1,500 range: competitive enough to confirm market viability, but distributed enough to allow new entrants to capture meaningful share. Combined with the other criteria in our profitable analyse de niche, HHI provides the structural foundation for basé sur les données product selection.