Japan postal code validator
How the postal code format works
- Format
- 7 digits, written as 000-0000
- Example
- 1000001
Things to watch for
- Format-only check — does not confirm the postal code actually exists
- 7 digits total; normally written with a hyphen after the first 3 digits (000-0000)
^[0-9]{7}$A Japanese postal code (yūbin bangō, 郵便番号) is the 7-digit code Japan Post uses to route mail, written as three digits, a hyphen, then four more — for example 100-0001 for Chiyoda, in central Tokyo. Unlike a flat run of digits, the code is hierarchical: the leading digits point to a broad delivery region, and the trailing digits progressively narrow that down to a specific town, block, or district. Anyone validating a Japanese shipping address or a checkout form needs the code in that exact 7-digit shape before it’s useful downstream.
Because the hyphen sits in a fixed spot — after the third digit — a code that’s missing it, or has digits transposed across that boundary, is easy to catch mechanically even without knowing what the code actually names. Catching that at the point of entry is cheaper than mail routed through Japan Post’s automated sorting machines to the wrong delivery zone.
How this validator works
This tool checks that the input is exactly 7 digits, accepted with or without the customary hyphen after the third digit, entirely in your browser, with nothing sent to a server.
What a pass doesn’t tell you
The code carries no check digit, so confirming it’s 7 digits in the right shape is the most a client-side tool can do — not that Japan Post has assigned it to a real town, ward, or building. Confirming that, and seeing exactly which area it names, requires Japan Post’s own postal code lookup.
Scope: this page and tool cover format validation only — not address lookup, ward or town matching, or confirming a code is currently in use.
postal code FAQ
What does the Japanese postal code actually encode?
It's hierarchical rather than a flat serial number. The first digits Japan Post assigns identify a broad prefecture-level delivery region, and the remaining digits progressively narrow that down to a city, ward, or town — occasionally down to a single large building in central Tokyo. That layered structure is different from postcodes that are just sequential blocks with no internal meaning.
Do I need to type the hyphen?
No — this validator accepts the code with or without the hyphen after the third digit (e.g. '1000001' or '100-0001'). The hyphen is a writing convention; the underlying code is still 7 digits.
Does a correctly formatted code mean it actually exists?
No. This tool only confirms the string is 7 digits in the right shape — it doesn't check it against Japan Post's actual assignment list. Confirming a code is real, and seeing exactly which town or ward it names, requires Japan Post's own postal code search.