Herfindahl-Hirschman Index (HHI) Calculator
Calculate the Herfindahl-Hirschman Index to measure market concentration.
Calculator
Results
HHI:
0
Market Concentration:
Unknown
Data Source and Methodology
All calculations are rigorously based on the standard HHI formula as recognized in economic analysis and competition law.
The Formula Explained
HHI = \(\sum_{i=1}^{N} s_i^2\)
Glossary of Variables
- Market Share (%): The percentage share of the market held by a specific firm.
- HHI: The sum of the squares of the market shares of all the firms in the market.
How It Works: A Step-by-Step Example
Consider a market with three firms having market shares of 40%, 35%, and 25%. The HHI is calculated as \(40^2 + 35^2 + 25^2 = 1600 + 1225 + 625 = 3450\).
Frequently Asked Questions (FAQ)
What is the Herfindahl-Hirschman Index (HHI)?
The HHI is a measure of market concentration to determine the competitiveness of a market.
How is HHI used?
HHI is used by regulatory agencies to assess the impact of mergers and acquisitions on market competition.
What are the thresholds for HHI?
HHI below 1500 indicates a competitive marketplace, 1500-2500 indicates moderate concentration, and above 2500 indicates high concentration.
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
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Formula (extracted text)
HHI = \(\sum_{i=1}^{N} s_i^2\)
Variables and units
- No variables provided in audit spec.
Sources (authoritative):
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - FTC — Consumer advice — consumer.ftc.gov · Accessed 2026-01-19
https://consumer.ftc.gov/
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.