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How the numbers are built

Calculation Methodology and Accuracy

A useful calculator must make both its arithmetic and its limitations visible. We use shared calculation engines, source registries and repeatable tests rather than rewriting formulas for each language.

01

Source hierarchy

  • Thai legislation, government departments and regulators.
  • Official tariff, tax, social-security and public-health publications.
  • Bank of Thailand and other authoritative financial education materials.
  • Standard mathematical formulas where no jurisdiction-specific rule applies.
02

Bilingual formula parity

Thai and English pages call the same underlying TypeScript formula. Translation changes labels and explanations, not arithmetic. Automated parity tests run identical inputs through the shared engine.

03

Rounding and estimates

Displayed values may be rounded for readability while calculations retain more precision. A provider or authority may use different rounding, billing periods, assessment bases, fees or case-specific rules.

04

Review cycle

  • Time-sensitive rates carry an effective period or review date.
  • Changes are checked against the primary source before updating a formula.
  • Corrections are applied to both languages and covered by regression tests.
  • Pages state material exclusions instead of presenting an estimate as an official result.

English content reviewed 23 July 2026.