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United Kingdom NHS number validator
How the NHS number format works
- Format
- 10 digits
- Example
- 9434765919
Things to watch for
- Weighted mod-11 checksum over the first 9 digits against the 10th
- If the computed check value is 10, the number is invalid outright, even if the format looks right
- Format + checksum only — does not confirm the number is actually assigned to a patient
- Scotland (CHI number) and Northern Ireland (H&C number) use different formats, not this one
^[0-9]{10}$An NHS number is the 10-digit identifier used for every patient registered with the NHS in England, Wales, and the Isle of Man — it appears on prescriptions, referral letters, appointment cards, and anywhere a GP surgery or hospital needs to reference your record precisely. It’s usually printed in three groups (3-3-4) for readability, though the number itself is just 10 digits run together. Scotland uses its own CHI number and Northern Ireland its own H&C number, so if you’ve been handed a number in one of those formats, this isn’t the right check.
How this validator works
This tool confirms the number is exactly 10 digits, then runs the same mod-11 check-digit calculation the NHS uses when issuing numbers: each of the first 9 digits is multiplied by a descending weight (10 down to 2), the products are summed, and the total is reduced modulo 11 to get an expected value. That value should match the 10th digit; if the calculation instead lands on 10, the number is structurally invalid and could never have been issued. Checking this catches a mistyped or transposed digit before it ends up in a form, spreadsheet, or patient record — entirely in your browser, with nothing sent to a server.
What a pass doesn’t tell you
A pass here only means the number is well-formed and internally consistent — not that it belongs to a real patient, is currently active, or matches the person in front of you. This tool does no lookup against any NHS database, sends nothing anywhere, and stores no personal data; it’s a pure offline format check, which is also why it’s safe to paste in a number without worrying about who might see it. To confirm a number is genuinely assigned to a patient, use official NHS verification channels — not a public web tool.
Content last reviewed 2026-07-09.
NHS number FAQ
How is an NHS number formatted?
It's 10 digits, conventionally written in a 3-3-4 pattern for readability — for example 943 476 5919 — though the underlying number has no spaces or separators. It appears on NHS cards, prescriptions, and correspondence for patients registered in England, Wales, and the Isle of Man.
What does the check digit actually check?
The 10th digit is a mod-11 checksum calculated from the first 9 digits, each multiplied by a descending weight from 10 down to 2, summed, and reduced modulo 11. If that calculation produces 10, the number is invalid outright and would never have been issued — a useful signal that a digit was mistyped or transposed.
Does this look up or confirm a patient?
No. This tool only checks that the number is correctly formatted and passes the check-digit calculation — it never looks up, stores, or transmits any patient data, and it can't confirm a number is actually assigned to someone. Scotland uses the CHI number and Northern Ireland uses the H&C number, both different formats this tool doesn't cover.