Most address forms were designed with a US or generic layout in mind, then had "County" bolted on for the UK. The result is forms that confuse visitors, data that is hard to print on a label, and deliveries that go astray. This guide sets out how a UK address is actually structured, what belongs in each box, and how to design a form around it.
The parts of a UK address
Written out for the post, a UK address is a stack of lines from the most specific to the least:
| Line | What it holds | Example |
|---|---|---|
| Addressee | The person or business receiving it. Not part of the address itself. | Ms J Okafor |
| Sub-building | Flat, unit, suite or floor within a larger building. Only some addresses have one. | Flat 4 |
| Building | A building name, a number, or both. Every address has one or the other. | 22 Castle Street |
| Locality | A village, district or estate name used when the street alone is ambiguous within the post town. Often absent. | Thorpe St Andrew |
| Post town | The town the delivery office serves. Always present, traditionally written in capitals. | NORWICH |
| County | Not needed for delivery. The post town and postcode already identify the place. | Norfolk |
| Postcode | Always the last line, in capitals with a space. | NR2 1PJ |
Two of these surprise people. The post town is not always the town someone would say they live in: it is the sorting-office town, so an address in a village may carry a nearby larger town as its post town. And the county is optional for delivery; the postal service stopped requiring it years ago, and many addresses are routinely written without one.
What goes in each form field
Forms do not have a "sub-building" box, so the parts above have to be fitted into the fields most form tools provide. The convention that works, and the one address data follows, is:
| Form field | Holds | Flat | House | Business |
|---|---|---|---|---|
| Address line 1 | Sub-building if there is one, otherwise the building | Flat 4 | 9 Marine Parade | Albion House |
| Address line 2 | The building when line 1 is a sub-building, or the locality | 22 Castle Street | 12 Albion Street | |
| Town / City | The post town | Norwich | Brighton | Leeds |
| County | Optional | Norfolk | East Sussex | West Yorkshire |
| Postcode | Always | NR2 1PJ | BN2 1TL | LS1 6PU |
Line 2 is the one to get right. It is empty for a plain house, holds the street for a flat, and holds the locality for an address in a village. Hiding it because "most people leave it blank" is the single most common cause of a flat number going missing.
Flats, floors and named buildings
- Flat 4, 22 Castle Street. The sub-building takes line 1, the building takes line 2. Written on one line it is "Flat 4, 22 Castle Street".
- Scottish tenement style: 3/2, 15 Rose Street. Floor and flat as a fraction. Keep it exactly as given in line 1.
- Named buildings without a number: The Old Bakery, Church Lane. The name is the building, so it goes in line 1 and the street in line 2.
- Named and numbered: Albion House, 12 Albion Street. The name in line 1, number and street in line 2. Couriers want the number; the name helps them find the door.
- Businesses. The company name belongs with the addressee, not in the address. Put it in a separate field or on the name line.
Formatting rules that avoid trouble
- Postcodes in capitals with a space:
NR2 1PJ, notnr21pj. Accept either when typing; store and print the formatted version. The postcode checker shows the correct form for any postcode. - No punctuation at line ends. Commas and full stops are not needed on a label and confuse parsers.
- Do not force a county. Marking it required makes people guess or invent one. If you ask at all, make it optional.
- Do not force a house number. Plenty of addresses have a name and no number. Validate that line 1 is present, not that it starts with a digit.
- Keep the parts separate. One big "Address" textarea is easy to build and impossible to print, sort or export reliably.
Mistakes that cause failed deliveries
- The flat number left out because line 2 was hidden or skipped.
- The town typed into the county box, or the locality typed as the town.
- A postcode with a letter O for a zero, or a digit missing, that passes a loose check.
- An old postcode for a new development, because the visitor copied it from the estate agent's listing.
- A business name as line 1 with the building dropped, so the courier reaches the street and no further.
Every one of these is avoided when the visitor picks their address from the list at their postcode rather than typing it. That is what postcode lookup is for, and why it is the standard for UK forms. If you run WordPress, BePostcodes does it for Gravity Forms, Contact Form 7 and WooCommerce, and fills exactly the fields described above.