What the six digits of an Indian PIN code mean

· 4 min read

India Post introduced the Postal Index Number on 15 August 1972 to speed up mail sorting and cut down on misdeliveries caused by place names that repeat across the country or are spelled several ways. The six digits encode a location hierarchically: each digit from the left removes ambiguity until only one delivery post office is left.

Digit 1 — the postal region

The first digit selects one of nine postal regions. Eight are geographic; the ninth is reserved for the Army Postal Service.

  • 1 — Delhi, Haryana, Punjab, Himachal Pradesh, Jammu & Kashmir, Ladakh, Chandigarh
  • 2 — Uttar Pradesh, Uttarakhand
  • 3 — Rajasthan, Gujarat, Dadra & Nagar Haveli and Daman & Diu
  • 4 — Chhattisgarh, Madhya Pradesh, Maharashtra, Goa
  • 5 — Andhra Pradesh, Karnataka, Telangana
  • 6 — Kerala, Tamil Nadu, Puducherry, Lakshadweep
  • 7 — West Bengal, Odisha, Arunachal Pradesh, and the rest of the North-East; Sikkim; Andaman & Nicobar Islands
  • 8 — Bihar, Jharkhand
  • 9 — Army Post Office (APO) and Field Post Office (FPO)

Digit 2 — the sub-region

The second digit identifies a sub-region — broadly a postal circle or a group of districts — within the first-digit region. Together the first two digits point at a postal circle: 11 is Delhi, 40 is Mumbai, 56 is Bengaluru, 70 is Kolkata, and so on.

Digit 3 — the sorting district

The third digit picks the sorting district inside that sub-region — usually aligned with a revenue district and served by one main sorting office that all mail for the area passes through. The first three digits together are the routing key: everything after them is about the last mile.

Digits 4 to 6 — the delivery post office

The final three digits identify the specific post office that delivers to the address, within the sorting district. 001 is typically the district’s Head Office; other offices are numbered without any geographic pattern, so you cannot infer distance or direction from them.

Because the last three digits point at one post office, there is no such thing as a single PIN code for a whole city. A large city is covered by many codes — you need the one for the specific locality.

Postal circles and the two-digit prefix

India Post organises its network into postal circles — broadly one per state or union territory, plus a separate circle for the Army Postal Service. The first two digits of a PIN code line up with these circles, which is why people who handle a lot of mail can often name the state from just the opening pair: 11 Delhi, 20 and 21 western Uttar Pradesh, 33 Gujarat, 44 Maharashtra, 45 Vidarbha, 56 Bengaluru, 60 Chennai, 68 Kerala, 70 Kolkata, 80 Bihar.

Region 9 is the exception to the geography: it is not a place at all. Codes beginning with 9 belong to the Army Postal Service and route to Field Post Offices and Army Post Offices, which move with the units they serve.

Worked example: 110001

  1. 1 — northern region
  2. 11 — Delhi postal circle
  3. 110 — the New Delhi sorting district
  4. 110001 — the delivery office for the Connaught Place area of New Delhi

The same reading works for any code. 400001 is region 4, the Mumbai circle (40), sorting district 400, delivery office 001 — the Fort area. 700001 resolves the same way for central Kolkata.

Can you locate a PIN code just by reading it?

Partly. The first three digits genuinely place you: region, then circle, then sorting district, each nested inside the last. The final three digits do not — offices within a district are numbered in the order they were assigned, not by position, so 400051 and 400052 need not be neighbours and a lower number is not "more central". Two codes that differ by one can sit several kilometres apart, and a large campus or market can hold a code of its own between two ordinary residential ones.

So the digits tell you the routing, not the street. To go from a code to an actual place — or the other way — look it up in the directory rather than reading the number.

Why this matters when you address mail

A correct PIN code lets sorting machinery route an item on the numbers alone, even if the handwritten address is messy. A wrong code sends it to the wrong sorting district first, adding days. When in doubt, detect the code for the exact location or look the locality up rather than guessing from a nearby address.