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15 characters · mod-36 check

GSTIN validator and decoder

Paste a GST number and see its state, embedded PAN, entity number and check character — plus exactly which part is wrong when it fails.

Fifteen characters. Case and spaces are normalised before checking.

Example:

The check runs in this tab. The GSTIN you paste is not uploaded, logged or stored.

Short answer: paste the number. A green verdict means the format and check character agree — a mistyped digit cannot survive that test. It says nothing about whether the registration exists.

What the fifteen characters are

Where people go wrong

The three common failures are a transposed pair of digits (the check character catches it), a state code that belongs to a different state than the address (the check character does not catch that), and a PAN typed from a different entity than the GSTIN was issued under. Only the first is arithmetic; the other two need the portal.

Checking the PAN on its own is faster when that is the only thing in doubt — thePAN validator reads its holder type. For the bank side of a payment, the IFSC finder checks a branch against a dated dataset.

GSTIN questions

Can this tell me whether a GSTIN is real?

No, and no browser page can. It verifies the format and the check character, which catches typing mistakes. Whether the number is registered, active, or belongs to the business you think it does can only be confirmed on the GST portal, which needs a login this page does not have.

How is the check character computed?

Each of the first fourteen characters is mapped to 0-35 (digits then letters), weighted 1 or 2 alternately, split into quotient and remainder mod 36, and summed. The fifteenth character is whatever makes that sum a multiple of 36. A single wrong digit therefore produces a different check character.

What does the embedded PAN tell me?

Characters 3 to 12 are the holder’s PAN. Its fourth letter is the holder type — P for an individual, C for a company, F for a firm or LLP, H for an HUF — so a GSTIN already says whether the registration is in a person’s or a company’s name.

Why do some states have two codes?

Because the state was reorganised. Andhra Pradesh kept 28 for undivided AP and received 37 after the 2014 bifurcation; 26 now covers Dadra and Nagar Haveli and Daman and Diu. 97 is “Other Territory” and 99 is the centre’s own jurisdiction, so neither is a state.

Is the number I paste uploaded?

No. The check is arithmetic on the string in this tab. A GSTIN is business-identifying data, so it is worth confirming in the network panel that the page made no request after loading.

Related tools

PAN validatorThe ten characters a GSTIN embeds.IFSC finderBranch details from a dated dataset.UPI ID validatorFormat check for a payment address.All lookupsReference data and ID checks.