Regex for Indian Vehicle Number Validation — RTO Format & BH Series Explained

Indian vehicle registration numbers follow a format issued by the Regional Transport Office (RTO), but forms that collect them rarely validate the structure properly. This guide breaks down the standard format, gives you a working regex, and covers the newer BH (Bharat) series that many teams forget to handle.

The Standard RTO Format

A typical Indian number plate looks like MH12AB1234 and breaks down into four segments:

• State code — 2 letters, e.g. MH (Maharashtra), DL (Delhi), KA (Karnataka)
• RTO code — 1 or 2 digits identifying the district RTO office, e.g. 12
• Series — 1 to 3 letters (sometimes just 1, sometimes 2), assigned sequentially as registrations are issued, e.g. AB
• Unique number — always 4 digits, e.g. 1234

Plates are printed without spaces, but many forms and older records store them with spaces or hyphens (MH 12 AB 1234 or MH-12-AB-1234), so your regex should tolerate both.

Regex for the Standard Format

// Matches MH12AB1234, MH 12 AB 1234, MH-12-AB-1234
const vehicleRegex = /^[A-Z]{2}[ -]?[0-9]{1,2}[ -]?[A-Z]{1,3}[ -]?[0-9]{4}$/;

function isValidVehicleNumber(input) {
  const normalized = input.trim().toUpperCase();
  return vehicleRegex.test(normalized);
}

isValidVehicleNumber('MH12AB1234');   // true
isValidVehicleNumber('DL-3C-AA-0001'); // true
isValidVehicleNumber('KA 05 MJ 2311'); // true
isValidVehicleNumber('MH1AB123');      // false — too few digits

The BH (Bharat) Series Format

Since 2021, vehicle owners with jobs that require frequent inter-state transfers (defence personnel, central government employees, employees of companies with offices in 4+ states) can opt for the BH series, which does not need re-registration when moving states. Its format is different: YY BH #### XX, e.g. 22 BH 1234 AB.

// Matches 22BH1234AB, 22 BH 1234 AB, 22-BH-1234-AB
const bhSeriesRegex = /^[0-9]{2}[ -]?BH[ -]?[0-9]{4}[ -]?[A-Z]{1,2}$/;

isValidVehicleNumber = (input) => bhSeriesRegex.test(input.trim().toUpperCase());

isValidVehicleNumber('22BH1234AB');      // true
isValidVehicleNumber('23 BH 5678 A');    // true

Combined Validator for Both Formats

In most real applications (insurance forms, parking apps, fleet management systems) you want to accept either format:

function isValidIndianVehicleNumber(input) {
  const value = input.replace(/[\s-]/g, '').toUpperCase();

  const standard = /^[A-Z]{2}[0-9]{1,2}[A-Z]{1,3}[0-9]{4}$/;
  const bhSeries = /^[0-9]{2}BH[0-9]{4}[A-Z]{1,2}$/;

  return standard.test(value) || bhSeries.test(value);
}

Common Edge Cases to Handle

• Some older plates use a single-letter series instead of two (e.g. DL1CA1234)
• Government vehicles sometimes use series like "GJ" without a numeric RTO code — always double-check against your actual data sample before shipping a strict pattern
• Diplomatic and military vehicles follow entirely different numbering systems and will fail both patterns above — treat them as a separate allow-list if your app must support them
• Always normalize casing and strip spaces/hyphens before matching so formatting differences don't cause false rejections
• Regex confirms format only — it does not verify the vehicle actually exists in the VAHAN database; use the government's VAHAN e-services API for that

Frequently Asked Questions