NPI Validator
ValidatorValidate NPI (National Provider Identifier) numbers. Checks the 10-digit format and recomputes the official Luhn check digit. Runs entirely in your browser.
About this tool
About NPI Validator
An NPI (National Provider Identifier) is a 10-digit number assigned by CMS to identify healthcare providers in the United States, used on virtually every claim, prescription, and referral in the US healthcare system. This validator confirms the format is correct and recomputes the check digit to verify the number is internally consistent, and identifies whether the number follows the pattern of an individual (Type 1) or organizational (Type 2) provider.
The validator strips whitespace and separators, verifies the 10-digit format, prepends the constant ISO/IEC 7812 issuer prefix '80840' to the first 9 digits, computes the Luhn check digit for the resulting 14-digit string, and compares it against the 10th digit. It also reads the first digit to classify the NPI as an individual or organizational provider.
Use this to verify an NPI collected on an intake form, claims submission, or provider directory before using it in a downstream system, to debug why an NPI is being rejected by a validation layer, or to sanity-check an NPI pasted from a CMS NPPES registry lookup.
Instant, fully client-side validation with no data ever leaving your browser. Note this checks structural validity only — it does not confirm the NPI is actually registered to a real, active provider, which requires a lookup against the CMS NPPES registry.
Key Features
- Full 10-digit format validation
- Recomputes and compares the official Luhn check digit
- Classifies the NPI as individual (Type 1) or organization (Type 2)
- Clear error messages for each failure mode
- Verified against real published test NPIs
- 100% browser-based, no data ever transmitted
FAQ
NPI Validator — Frequently Asked Questions
What is an NPI number?
NPI stands for National Provider Identifier, a 10-digit number assigned by CMS to every healthcare provider and healthcare organization in the United States. It replaced a patchwork of payer-specific provider numbers with a single, standardized identifier used across the entire US healthcare system.
How is the NPI check digit calculated?
Take the first 9 digits, prepend the constant string '80840' (the ISO/IEC 7812 issuer prefix CMS was assigned), and run the standard Luhn algorithm — doubling every second digit from the rightmost, summing the digits of each product, and subtracting the total from the next multiple of 10 — on the resulting 14-digit string. The result must equal the 10th digit.
How can I tell if an NPI belongs to an individual or an organization?
The first digit tells you: 1 means a Type 1 NPI, assigned to an individual provider such as a physician or nurse. 2 means a Type 2 NPI, assigned to an organization such as a hospital, clinic, or group practice.
Why does my NPI fail validation?
The most common cause is a single mistyped or transposed digit. Also confirm the number is exactly 10 digits with no letters, spaces, or dashes — some forms and databases store NPIs with formatting that needs to be stripped first.
Does a valid NPI mean the provider is currently active?
No. This validator only confirms the number is structurally well-formed and its check digit is correct — that's necessary but not sufficient. To confirm an NPI is currently registered and active, and see the provider's name and specialty, look it up in the CMS NPPES registry.
Tips
- Strip spaces and dashes before validating — some intake forms and databases format NPIs with separators that aren't part of the official number
- If the check digit fails, try re-copying the NPI from its original source — the most common error is a single transposed digit
- The first digit tells you the provider type at a glance: 1 for individuals, 2 for organizations
- This validator never sends your NPI anywhere — the check digit is recomputed entirely in your browser
Explore more
Related Tools
Other tools that might be useful for your workflow