Check an NPI and look up the provider.
Type a 10-digit NPI. The page checks its check digit as you type. Look it up to see the provider's name, credential, specialty and location, and how many marketplace and Medicare Advantage plans list them.
10 free lookups a day for each visitor, shared by the three tools. Format checks in the page are free and unlimited.
Type an NPI to check it. The check runs in your browser and does not use a lookup.
How the NPI check digit works.
The tenth digit of an NPI is a check digit. It is calculated from the first nine digits with the Luhn formula, the same formula used for credit card numbers. Here it is for NPI 1376006148.
- 1Take the first nine digits: 137600614.
- 2Start at the rightmost of the nine and double every other digit: 4, 6, 0, 7 and 1 become 8, 12, 0, 14 and 2. If a result is 10 or more, add its two digits: 12 becomes 3, 14 becomes 5.
- 3Add everything up: 8 + 1 + 3 + 0 + 0 + 6 + 5 + 3 + 2 = 28. Add 24 for the fixed prefix 80840 that every NPI shares: 52.
- 4The check digit brings the total up to the next multiple of 10: 52 needs 8. The tenth digit of 1376006148 is 8, so the NPI is valid.
What a valid check digit tells you.
It tells you the number is well formed. The check catches every single mistyped digit and most swaps of two neighbouring digits, so it is a good first test in any form that asks for an NPI.
It does not tell you that the number belongs to a provider. Look the NPI up to see whether a provider uses it, who they are, and which plans list them.
Get a free key for 500 calls a month.
The tools give 10 lookups a day. The API gives the same answers in your own code: every plan that lists a provider, checks for a provider and a plan, and plan details, each with its source type and date.