📮UK Postcode Checker

About this tool

Paste postcodes, one per line, in any case and spacing. Each is validated and formatted with a single space, split into area, district, sector and unit, and given its postcode area name. Copy all the valid ones, cleanly formatted, in one go.

How UK postcodes are structured

A UK postcode has an outward code, the area and district such as SW1A or M1 used to route mail to a delivery office, and an inward code, the sector digit and two-letter unit such as 1AA that narrow it to a street or building. The area is one or two letters: there are 121 postcode areas from AB (Aberdeen) to ZE (Shetland), plus Guernsey (GY), Jersey (JE) and the Isle of Man (IM). The district is one or two digits, sometimes followed by a letter in central London. The inward code is always a digit followed by two letters, and those letters never include C, I, K, M, O or V, to avoid confusion when handwritten. Valid formats are A9 9AA, A99 9AA, AA9 9AA, AA99 9AA, A9A 9AA and AA9A 9AA, written in capitals with one space before the inward code. The checker applies those rules, recognises the special GIR 0AA and BFPO codes, and tidies messy input from forms and exports. Honest limits: a correct format doesn't prove a postcode exists or is current, because new postcodes are added and old ones retired. Royal Mail's Postcode Address File is the authoritative source. The phone number formatter and the distance between coordinates tool are related.

Frequently asked questions