Effective Number of Thai Provinces, Sections and Codes (2026)
In short
Thailand's 77 provinces behave like just 2.45 equal-sized ones when revenue is the yardstick, as of 17 July 2026. The 21 industry sections behave like 2.97. The 1,196 five-digit industry codes behave like 39.08. Bangkok alone books 63.14 percent of provincial revenue. Wholesale and retail books 48.38 percent of section revenue. Thai revenue sits on a handful of places and two sectors, but it spreads across hundreds of codes.
How many provinces does Thai revenue really have?
About 2.45. That is the effective number of provinces, the count of equal-sized provinces that would produce the same concentration as the real revenue split across 77 provinces (DBD, 2026). The trick is simple. Square each province's share of revenue, add the squares to get a Herfindahl index of 0.4085, then take one divided by that index. Bangkok does most of the work, with 63.14 percent of the 80.06 trillion baht reported by companies that name a province. The 21 industry sections come out at 2.97, because wholesale and retail holds 48.38 percent and manufacturing holds 31.38 percent. The 1,196 five-digit codes with revenue come out at 39.08. Codes are far more evenly spread than places.
Effective number versus the real count
- 77 provinces2
- 21 industry sections3
- 1,196 five-digit codes39
Figures in effective number of equal-sized units.
Each bar is one divided by the Herfindahl index of revenue shares. The real counts are 77, 21 and 1,196.
Real count against effective count
| Level | Real count | Effective number | Effective as share of real | Largest single share |
|---|---|---|---|---|
| Provinces | 77 | 2 | 3.2% | 63.14% in Bangkok |
| Industry sections | 21 | 3 | 14.1% | 48.38% in wholesale and retail |
| 5-digit TSIC codes | 1,196 | 39 | 3.3% | 12.79% in the top code |
Herfindahl index and effective number by level, as of 17 Jul 2026.
Share of provincial revenue, top eight provinces
- Bangkok63
- Samut Prakan6
- Chon Buri5
- Rayong4
- Pathum Thani3
- Nonthaburi2
- Ayutthaya2
- Samut Sakhon2
Figures in percent of revenue.
Bangkok is larger than the next seven provinces combined, and the remaining 69 together hold the last 13.90 percent.
Take out the giants and the picture changes
Remove Bangkok and the other 76 provinces have an effective number of 13.76. That is still small, but it is more than five times the figure with Bangkok in. Remove wholesale and retail and manufacturing from the section list and the other 19 sections have an effective number of 9.05. Two sectors turn a 21-way economy into a three-way one. The code level tells a gentler story. The largest single code holds 12.79 percent of revenue, and the top 100 codes hold 75.13 percent, so there is a long tail that adds up to something.
Why this matters
One city carries nearly two thirds of what companies report, so a hit to Bangkok is a hit to the national revenue line. Lenders, insurers and investors who diversify across provinces are diversifying less than the map implies. The same is true across sections, where picking any two of the 21 mostly means picking trade and factories. Diversifying across five-digit codes is the one route that genuinely spreads risk. Anyone building a regional strategy should read 2.45, not 77, as the number of markets on the table.
Definitions
- Herfindahl index
- The sum of squared shares. It runs from near zero for an even split to one when a single unit holds everything.
- Effective number
- One divided by the Herfindahl index. It is the number of equal-sized units that would show the same concentration.
- TSIC
- Thailand Standard Industrial Classification, with 21 lettered sections and five-digit codes below them.
- Aggregate revenue
- The sum of revenue reported by companies that filed a financial statement.
Assumptions
- Only companies with a filed financial statement contribute revenue.
- Revenue is assigned to the registered province, so head offices in Bangkok can pull revenue away from the places where goods are made or sold.
- One province row with no name, 556 companies, is excluded from the province index. Including it moves the effective number from 2.448 to 2.450.
- Revenue of a corporate group can be counted in more than one company, so totals are not consolidated.
Methodology
Source: Department of Business Development registry aggregates, rows computed on 17 July 2026 and treated as of that date. Revenue is the total reported revenue of companies that filed a financial statement, grouped by registered province, TSIC section and five-digit TSIC code. The effective number is one divided by the sum of squared revenue shares, a Herfindahl-based equivalent count. The province figure uses the 77 named provinces, which excludes one unlabelled row of 556 companies with 24.4 billion baht, and the code figure uses the 1,196 codes with positive revenue. Registered location is not always where revenue is earned, so head-office provinces are favoured. Shares are computed here, not published by the registry.
How we verified this
- Province Herfindahl index recomputed from 77 named provinces: sum of squared shares is 0.408497, and 1 / 0.408497 = 2.448, shown as 2.45.
- Bangkok share recomputed: 50,545,042,342,775 / 80,057,095,437,018 = 63.14 percent.
- Section Herfindahl index across 21 sections is 0.337072, and 1 / 0.337072 = 2.967, shown as 2.97.
- Wholesale and retail 38,739,274,707,313 / 80,075,153,974,806 = 48.38 percent, and manufacturing 25,130,983,654,715 / 80,075,153,974,806 = 31.38 percent.
- Code Herfindahl index across 1,196 codes with revenue is 0.025588, and 1 / 0.025588 = 39.08.
- Excluding Bangkok, the 76-province index is 0.072689 and 1 / 0.072689 = 13.76. Excluding sections G and C, the 19-section index is 0.110508 and 1 / 0.110508 = 9.05.
- Effective share of real count: 2.448 / 77 = 3.2 percent, 2.967 / 21 = 14.1 percent, 39.08 / 1,196 = 3.3 percent.
- Top eight province revenues sum to 86.10 percent of the 80,057,095,437,018 baht total, so the remaining 69 hold 13.90 percent.
References
- Department of Business Development. (2026). Registered juristic persons and financial statement aggregates. Ministry of Commerce, Thailand. https://www.dbd.go.th/
- Laakso, M., & Taagepera, R. (1979). "Effective" number of parties: A measure with application to West Europe. Comparative Political Studies, 12(1), 3-27. https://doi.org/10.1177/001041407901200101
Frequently asked questions
What is an effective number?
It is the count of equal-sized units that would give the same Herfindahl index as the real shares, calculated as one divided by the sum of squared shares (Laakso & Taagepera, 1979).
How many effective provinces does Thailand have by revenue?
2.45 out of 77, as of 17 July 2026, driven by Bangkok's 63.14 percent share (DBD, 2026).
Are industry codes more concentrated than sections?
No. Sections have an effective number of 2.97 out of 21, while the 1,196 codes with revenue have 39.08, which is a much larger share of the code count than for provinces.
Does this mean the other 76 provinces do not matter?
No. Without Bangkok the other 76 provinces have an effective number of 13.76, so regional markets are real, just small beside the capital.
Cite this page
Chatpong L. (2026). Effective Number of Thai Provinces, Sections and Codes (2026). Max Data Insights. https://maxdatathailand.com/insights/effective-number-of-thai-provinces-sections-and-codes-by-revenue-2026
Data & corrections
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Written by
Chatpong L.Founder, Max Data, Max Solutions Co., Ltd.
Chatpong L. leads Max Data, a company-intelligence platform built on Thailand's official business registry. He writes about the structure of the Thai economy using primary registry data. His work covers company formation, industry concentration, and regional business activity.
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This page reports company-level and aggregate statistics only. It names no individuals and makes no claims about any person. Figures are provided for information and may be revised as source data updates.