HHI Calculator
Calculate the Herfindahl-Hirschman Index to measure market concentration
Market Share Input
Market Concentration Results
HHI Interpretation
Enter market shares to calculate HHI and see market concentration analysis.
About the Herfindahl-Hirschman Index
The HHI is a commonly accepted measure of market concentration used by economists and antitrust regulators to evaluate competitive markets.
HHI Formula
HHI = ∑ (Market Share of Firmi)2
For each firm, square its market share percentage (as a whole number), then sum all these squared values.
HHI Classification (US DOJ Guidelines)
| HHI Range | Market Concentration | Regulatory Concern |
|---|---|---|
| Below 1,500 | Unconcentrated | None |
| 1,500-2,500 | Moderately Concentrated | Possible scrutiny |
| Above 2,500 | Highly Concentrated | Likely antitrust concerns |
Frequently Asked Questions
Understanding Market Concentration with HHI
Our free HHI calculator provides an easy way to quantify market concentration for economic analysis, competitive assessment, or antitrust evaluation. The Herfindahl-Hirschman Index offers several advantages over simple concentration ratios:
- ▸ Sensitive to distribution – Gives more weight to larger firms
- ▸ Standardized metric – Allows comparison across industries
- ▸ Regulatory acceptance – Used by US DOJ, FTC, and EU Commission
The calculator works entirely in your browser – no data is sent to servers, ensuring complete privacy for your market analysis.