United States NPI validator
How the NPI format works
- Format
- 10 digits
- Example
- 1234567893
Things to watch for
- Checksum works by prepending the constant prefix 80840 to the first 9 digits and running the standard Luhn algorithm over the result
- Format + checksum only — does not confirm the provider is actually registered in NPPES or currently active
- There are two types: Type 1 (individual providers) and Type 2 (organizations) — both use the same 10-digit format and checksum
^[0-9]{10}$A US NPI (National Provider Identifier) is the 10-digit number CMS issues, through its NPPES system, to every healthcare provider in the country — individual clinicians and organizations alike. It’s the identifier that shows up on HIPAA-mandated claims and other healthcare transactions to say who provided the care. Unlike some ID numbers, an NPI’s digits don’t encode a state, specialty, or name; it’s just a number with one built-in safeguard — a check digit — designed to catch exactly the kind of typo that can get a claim rejected.
How this validator works
This tool checks that the input is 10 digits, then reconstructs the calculation CMS actually uses to validate an NPI: prepend the constant 80840 — the ISO 7812 issuer prefix assigned to the health industry — to the first 9 digits, then run the standard Luhn algorithm (the same checksum used on credit card numbers) over that 15-digit string. The result has to match the 10th digit. Because a mistyped or transposed digit almost always breaks this checksum, validating it catches the single-character slip that turns a correct NPI into a rejected claim, before you submit anything. Everything runs client-side, in your browser, with nothing sent to a server.
What a pass doesn’t tell you
A pass here confirms the NPI is well-formed and internally consistent — not that it belongs to a real, currently active provider, or that it’s the provider you intended. NPI digits carry no embedded identity information, so a valid-looking number that’s simply never been issued will still fail the checksum, but a valid, issued NPI reveals nothing about who holds it just from the digits. To confirm a provider’s identity and status, look up the NPI for free in the NPPES NPI Registry, the CMS system that issues and administers every NPI.
Scope: this page and tool cover NPI format and Luhn check-digit validation only — not provider registration status, license verification, or confirming which entity a given NPI belongs to. Use this validator to catch a mistyped NPI before it holds up a claim; use the NPPES Registry to confirm the provider behind the number.
Content last reviewed 2026-07-09.
NPI FAQ
What is the 80840 prefix?
80840 is the ISO 7812 issuer prefix CMS assigns to the US healthcare industry. It isn't stored anywhere on the NPI itself — the checksum works by mentally prepending 80840 to the first 9 digits of the NPI, then running the standard Luhn algorithm over the resulting 15-digit string. The last digit of that calculation must match the NPI's 10th digit.
Does a valid NPI mean the provider is active and registered?
No. This tool only confirms the number is correctly formatted and passes the Luhn check digit — it does not query CMS, so it can't tell you if the provider is currently registered, active, or who they are. For that, use the free NPPES NPI Registry lookup on the CMS website.
What's the difference between an individual and organizational NPI?
Type 1 NPIs identify individual providers (doctors, nurses, therapists); Type 2 NPIs identify organizations (hospitals, clinics, group practices). Both use the identical 10-digit format and the same Luhn checksum, so this validator checks them the same way — the type isn't encoded in the digits.