Free tool
UK postcode format checker
Type a postcode and see whether it is written correctly, how it should be formatted, and what each part means. Runs in your browser; nothing is stored or sent.
Start typing to check the format.
- Area
- District (outward code)
- Sector
- Unit (inward code)
A valid format does not mean the postcode is in use. To find the real addresses at a postcode, use a lookup.
- Check for the letter O where a zero should be, or the letter I instead of a one.
- The last three characters are always a digit then two letters, for example 2NH.
- The first part starts with one or two letters, then one or two digits, and sometimes a letter: EH2, LS1, SW1A, EC1A.
How a UK postcode is built
Every UK postcode has two halves separated by a space. The outward code gets the post to the right delivery office; the inward code gets it to the right street or building.
| Part | Example in EH2 2NH | What it is |
|---|---|---|
| Area | EH | One or two letters. Roughly a city or region: EH is Edinburgh, LS is Leeds, BS is Bristol. |
| District | EH2 | The area plus one or two digits, sometimes with a letter, such as SW1A or EC1A. This is the outward code. |
| Sector | EH2 2 | The district plus the first digit of the inward code. A few thousand addresses. |
| Unit | EH2 2NH | The full postcode. Typically a street, part of a street, or a single large building. |
The mistakes we see most in forms
- Letters for digits.
SW1A 0AAtyped asSW1A OAAlooks almost the same on screen, but with a letter O in place of the zero it is not a postcode. The checker rejects O, I and other letters where a digit belongs. - The missing space.
EH22NHis fine to type and most systems accept it, but the formatted version always has the space before the last three characters. - Lower case. Harmless, but standardise to upper case before storing or printing.
- Half a postcode. An outward code alone, such as
EH2, identifies a district, not an address. It is not valid as a delivery postcode. - Letters that never appear. The inward code never uses C, I, K, M, O or V, which is why a postcode ending in
2NOcannot be right.
Checking the format is not the same as finding the address
A format check tells you a postcode could exist. It cannot tell you whether it does, or which addresses are at it, or stop someone typing a perfectly valid postcode for the wrong street. That is what postcode lookup is for: the visitor types their postcode, picks their address from the list, and the form fills itself with a complete, current address.
If you run a WordPress site, that is what BePostcodes does for Gravity Forms, Contact Form 7 and WooCommerce, from £6 a month.
Questions
- Does this check that the postcode exists?
- No. It checks that the text is shaped like a UK postcode, with a valid outward and inward part. Whether that postcode has addresses at it is a lookup, which is what the BePostcodes plugins do inside a form.
- What does a valid UK postcode look like?
- One or two letters, one or two digits and sometimes a letter, a space, then a digit and two letters. For example EH2 2NH, LS1 6PU, BS1 5TR or SW1A 1AA. The space is optional when typing but always shown when formatted.
- Why is my postcode showing as invalid?
- Usually a letter O typed instead of a zero or a letter I instead of a one, a missing character, or a character in the wrong place. The checker shows which part failed so you can compare.
- Is anything I type sent anywhere?
- No. The check runs in your browser and nothing is sent to BePostcodes or anyone else.