What does it mean to verify an NPI number?

Here it means two things: confirming the number has a valid NPI format (10 digits with a correct check digit), and finding whether a matching public record exists in CMS NPPES. It does not verify a provider's license.

How is an NPI check digit calculated?

NPIs use the Luhn algorithm applied to the number prefixed with 80840. If the check digit is wrong, the number is not a valid NPI format.

A number passes the format check — is the provider verified?

No. A valid format only means the number is well-formed and may exist in NPPES. It says nothing about licensure, credentialing, certification, or quality.

Format check + public lookup

Verify an NPI Number

Check whether a 10-digit NPI has a valid format, then look up the matching public record in CMS NPPES.

We'll check the number format (10 digits, valid check digit) before looking up the public NPPES record.

What this tool checks

This tool performs a format check on the NPI you enter. A valid NPI is exactly ten digits and includes a check digit calculated with the Luhn algorithm (using the standard 80840 prefix). If the format is valid, you can open the matching public record from CMS NPPES.

“Verify” here refers only to the number format and the presence of a public NPPES record. It does not confirm that the provider holds an active license, is board certified, is in good standing, or participates in any insurance plan.

Frequently asked questions

What does it mean to verify an NPI number?: Here it means two things: confirming the number has a valid NPI format (10 digits with a correct check digit), and finding whether a matching public record exists in CMS NPPES. It does not verify a provider's license.
How is an NPI check digit calculated?: NPIs use the Luhn algorithm applied to the number prefixed with 80840. If the check digit is wrong, the number is not a valid NPI format.
A number passes the format check — is the provider verified?: No. A valid format only means the number is well-formed and may exist in NPPES. It says nothing about licensure, credentialing, certification, or quality.