Italy CAP validator
How the CAP format works
- Format
- 5 digits
- Example
- 00184
Things to watch for
- Format-only check — does not confirm the CAP actually exists
- Always exactly 5 digits with no separators
^[0-9]{5}$An Italian CAP (Codice di Avviamento Postale) is the 5-digit postcode Poste Italiane uses to route mail, written after the city name — for example 00184 in Rome. Anyone validating a shipping address, a checkout form, or a spreadsheet of Italian customer records needs the CAP to be the right length and shape before it’s trusted downstream.
Because the code is a plain run of 5 digits with no separator, a dropped or duplicated digit is easy to miss by eye but still produces something that reads as a plausible CAP. Catching that at data entry matters more in Italy than in some neighboring countries, since CAPs are grouped around postal hubs rather than one-to-one with a single province or town — so a subtly wrong code can still look locally reasonable.
How this validator works
This tool checks that the input is exactly 5 digits with no letters, spaces, or punctuation, entirely in your browser — nothing is sent to a server, and there’s no signup.
What a pass doesn’t tell you
A CAP carries no check digit, so a correctly shaped 5-digit string is the most a client-side check can confirm — not that Poste Italiane has assigned it to the comune typed alongside it on a form. Confirming that requires Poste Italiane’s own postcode lookup.
Scope: format validation only — not address lookup, comune matching, or confirming a code is currently in use.
CAP FAQ
What does CAP stand for?
CAP is short for Codice di Avviamento Postale, Italy's 5-digit postcode. It's written after the city name, for example 00184 for a district of central Rome.
Why do several nearby Italian towns sometimes share the same CAP?
Unlike systems where two digits map cleanly to one province, Poste Italiane groups CAPs around postal sorting hubs rather than strict province boundaries, so a cluster of small comuni near a larger town can share the same 5-digit code. A format check can't distinguish those cases — only Poste Italiane's own address list can confirm which comune a CAP actually resolves to.
Does a correctly formatted CAP mean it actually exists?
No. This tool only confirms the string is 5 digits — it doesn't check the code against Poste Italiane's actual list of assigned comuni. Confirming a CAP is real requires Poste Italiane's own postcode lookup.