What are the 15 characters of a GSTIN made of?

Two digits for the state code, the entity's 10-character PAN, one entity/registration digit, a default Z, and a final check digit. The validator inspects each segment separately and reports which one fails.

How is the GSTIN check digit computed?

Each of the first 14 characters is mapped to a base-36 value, multiplied by an alternating factor of 1 and 2, and the base-36 digits of each product are summed. The check value is (36 minus sum-mod-36) mod 36, mapped back to a character.

Does a valid GSTIN mean the supplier is genuine?

No. A valid check digit and structure only prove the number is well-formed. Always confirm the GSTIN is active and matches the supplier's legal name on the official GST portal before claiming input-tax credit.

Can I read the PAN out of a GSTIN?

Yes. Characters 3 to 12 of the GSTIN are the entity's PAN in the standard AAAAA9999A pattern. The validator extracts and pattern-checks it, which is a quick way to cross-verify a supplier's PAN against their GSTIN.

Is the GSTIN sent to any server?

No. Validation runs entirely in your browser, so the GSTIN you paste never leaves your device. That makes it safe for bulk-checking vendor master data offline.

India GSTIN Validator

Validate an Indian GSTIN before you trust the invoice

A GSTIN is the 15-character identifier every GST-registered business in India carries. A wrong GSTIN on a purchase invoice can block your input-tax credit. This validator checks every part of the number — including the official check digit — and tells you the issuing state, all in your browser.

How it works

The validator inspects the GSTIN segment by segment:

State code (chars 1–2) is looked up against the official list (for example 27 = Maharashtra, 07 = Delhi).
PAN (chars 3–12) must match the pattern AAAAA9999A.
Entity digit (char 13) must be alphanumeric.
Default Z (char 14) is normally the letter Z.
Check digit (char 15) is recomputed with the GSTN algorithm.

The check digit uses base 36: each of the first 14 characters is valued 0–35, multiplied by an alternating factor (1, 2, 1, 2, …), and the tens and units of each product (in base 36) are summed. The check value is (36 − sum mod 36) mod 36, mapped back to a character.

Example and notes

27AAPFU0939F1ZV validates cleanly: state 27 is Maharashtra, the embedded PAN AAPFU0939F matches the pattern, position 14 is Z, and the computed check digit is V — matching the supplied digit.

A passing result confirms the number is structurally sound and self-consistent. It does not confirm the registration is active or that the legal name matches. For purchase decisions and credit claims, always cross-check on the GST portal.