What Each Digit in a PIN Code Means
India's 6-digit Postal Index Number (PIN) looks like a random string of digits — but it isn't. Each position encodes a specific piece of geographic information, from the broad region all the way down to the individual post office that delivers your mail.
The Structure of a PIN Code
Digit 1 — Postal Zone
Divides India into 8 geographic zones (1–8) plus one special zone (9) for the armed forces. This is the highest level of the hierarchy — think of it like a region code.
Digit 2 — Sub-Zone
Together with digit 1, the first two digits identify a sub-zone — typically a state or group of closely related states within a zone. For example, 11 = Delhi, 40 = Mumbai region, 60 = Chennai region.
Digit 3 — Sorting District
The third digit identifies the sorting district — the postal district responsible for sorting and forwarding mail. Each sorting district has a central sorting office (usually co-located with the Head Post Office). The first three digits together — for example, 110 — uniquely identify a sorting district (in this case, Delhi).
Digits 4, 5, 6 — Delivery Post Office
The last three digits identify the specific post office that delivers mail to your address. These are assigned sequentially within each sorting district, starting at 001 which is always the Head Post Office (HO) of that district. Sub Offices and Branch Offices follow with higher numbers.
First Digit — Zone Reference
| Digit | States / Territories |
|---|---|
| 1 | Delhi, Uttar Pradesh, Uttarakhand, Himachal Pradesh, Jammu & Kashmir, Ladakh |
| 2 | Haryana, Punjab, Chandigarh, Rajasthan |
| 3 | Gujarat, Daman & Diu, Dadra & Nagar Haveli |
| 4 | Maharashtra, Goa |
| 5 | Telangana, Andhra Pradesh, Karnataka |
| 6 | Kerala, Tamil Nadu, Puducherry, Lakshadweep |
| 7 | West Bengal, Odisha, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, Andaman & Nicobar Islands, Sikkim, Assam |
| 8 | Bihar, Jharkhand |
| 9 | Army Post Office (APO) and Field Post Office (FPO) |
Reading a PIN Code — Example
Take PIN code 400001 (Mumbai GPO):
- 4Zone 4 → Maharashtra & Goa
- 0Sub-zone 40 → Mumbai region
- 0Sorting district 400 → Mumbai City
- 001Post office 001 → Mumbai GPO (Head Office)
You can look up any PIN code and see its post office type, GPS coordinates, and district on indianpincode.com.