Apply healthcare provider identifier rules.
Initialising algorithm engine for NPI Check Digit Calculator...
How NPI Check Digit Calculator Works?
The NPI Check Digit Calculator works by prefixing the 9-digit National Provider Identifier (NPI) payload with 80840 and applying the Luhn algorithm. Adding the constant 24 to the Luhn sum of the 9 digits gives the same result.
- 1Enter the first 9 digits of the 10-digit NPI.
- 2Double every second digit starting from the rightmost (positions 9, 7, 5, 3, 1).
- 3Add all digits of the results and the undoubled digits.
- 4Add 24 to account for the 80840 prefix.
- 5Append (10 − (S mod 10)) mod 10 as the 10th digit.
NPI Check Digit Calculator Formula
The NPI formula is Check = (10 − ((24 + Luhn sum of 9 digits) mod 10)) mod 10.
S = 24 + Σ f(dᵢ), i = 1…9 Check = (10 − (S mod 10)) mod 10 (NPI) (24 = Luhn contribution of prefix 80840)
80840is the ISO 7812 prefix for US health applications.
Luhn sum of 123456789 = 43 S = 24 + 43 = 67 Check = 3 NPI = 1234567893
NPI Check Digit Calculator Conversion Table
The NPI conversion table lists sample 9-digit payloads with their NPI check digit.
| Payload | Luhn sum | Sum + 24 | Check digit | NPI |
|---|---|---|---|---|
| 123456789 | 43 | 67 | 3 | 1234567893 |
| 100000000 | 2 | 26 | 4 | 1000000004 |
| 199999999 | 74 | 98 | 2 | 1999999992 |
| 245319481 | 41 | 65 | 5 | 2453194815 |
| 112345678 | 40 | 64 | 6 | 1123456786 |
What is NPI Check Digit Calculator?
An NPI Check Digit Calculator is a tool that computes the 10th digit of a US National Provider Identifier. The Centers for Medicare & Medicaid Services (CMS) issues NPIs to doctors, hospitals, and other covered providers.
NPIs start with 1 or 2 and carry no information about the provider. The check digit follows ISO/IEC 7812 with the 80840 prefix.
What are the uses of NPI Check Digit Calculator?
There are 3 main uses of the NPI Check Digit Calculator, including claims processing, credentialing, and EHR data entry.
- Claims processing: Billing systems validate NPIs before submitting claims.
- Credentialing: Health plans check provider NPIs during enrolment.
- EHR data entry: Electronic health record systems reject mistyped NPIs.