NPI Number Validator (US)

About the NPI Number Validator (US)

A National Provider Identifier (NPI) is the 10-digit number every HIPAA-covered health care provider in the United States uses on claims, superbills and credentialing files. Its last digit is a check digit: CMS computes it with the Luhn formula as if the card prefix 80840 came first, so most typing mistakes — one wrong digit, two neighbouring digits swapped — make the number fail the check.

Type or paste one NPI to see whether it passes and the working step by step, or paste a whole list — a column from a spreadsheet, a roster of providers — or open a CSV file and pick its NPI column. Each number that fails says why: not 10 digits, characters that are not digits, a first digit other than 1 or 2, or the wrong check digit (with the digit it should be). The check runs in your browser; nothing is sent anywhere.

It tells you whether a number is well formed, not whether it is assigned or to whom: look that up in the official NPI Registry.

One number is checked and explained in full for everyone. For a pasted roster or a file the free preview shows every count and the first rows of the table; the rest of the table, the CSV report and the copied list of valid numbers unlock with a Pro pass.

Common uses

• Checking a provider’s NPI before it goes in box 24J or 33a of a claim, or on a superbill.
• Cleaning a roster or a credentialing spreadsheet: the bad rows are marked in the file itself.
• Testing the NPI field of your own billing software with known good and bad numbers.

How the check digit works

CMS describes the calculation in its NPI check digit requirements:

• double every other digit of the first nine, starting with the ninth (positions 9, 7, 5, 3 and 1);
• add the digits of those products (14 counts as 1 + 4) to the four digits that were not doubled, and add 24 — the sum the prefix 80840 would contribute;
• subtract the total from the next number ending in zero: that is the check digit (0 when the total already ends in zero).

The constant 24 is why a plain Luhn check of the ten digits, as for a card number, gives a different answer: 1234567893 fails it, while 808401234567893 passes. The Luhn Validator runs that plain check; this page adds the prefix for you.

What a valid result does and does not mean

A number that passes has the right length, starts with 1 or 2 (CMS issues NPIs with one of those first digits) and has the right check digit. It may still not be assigned, belong to another provider, or have been deactivated. An NPI has no meaning built into it: you cannot tell an individual (type 1) from an organization (type 2), or a specialty or state, from the digits. The NPI Registry shows who an NPI belongs to.

Limitations

• A format check only: it does not look numbers up in the NPI Registry, so it cannot say whether an NPI is assigned, active or the right provider’s.
• Up to 20,000 numbers at a time; the table shows the first 500 of them and the CSV report has them all.

Privacy

On this device: nothing is sent

Everything is checked in your browser. The numbers you type and the files you open are not uploaded or stored.