[philo23]

Kinda meta, but this is the first time in a long time where I've put only the first half of my postcode in expecting it not to work and been surprised. Most of these "find your nearest XYZ" site require the full postcode which is just unnecessary unless you're looking for a fairly precise location. A full postcode can narrow your location down to an individual street, so its nice not to give too much away if you can.

For anyone not in the know, UK postcodes are made up of two parts: a general area (the outward code) and then a more specific one (the inward code.) Generally speaking a postcode + house number will be good enough to get a letter delivered to the right place, though the sorting office might not be too happy with you...

The format [0] is roughly: AB12 3CD, though the number of letters/numbers on the left side can vary a bit. As far as I know the second set of numbers is always 1 digit though, so that's how you can easily split the two sides of it to format it nicely. There's a couple of special ones that break the rules though.

[0] https://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdo...

[alexfoo]

I agree with the bit about the having to enter a full postcode on some sites, I often use one nearby or, if they make me select a specific address for no valid reason I make sure I use a random address nearby. Apologies to some of my neighbours who might be bombarded with junk mail for services I’ve once been half interested in.

A full postcode is often much less than a single street.

Picking something at random stick “SW15 6DZ” into Google maps and you’ll see it only covers 6 buildings (most are individual houses but some are split into flats). According to the Royal Mail address finder site there are only 12 unique delivery addresses that share that postcode. The Western half of that road has 12 or so full postcodes for only 100 houses.

A full postcode and one other bit of information can often be enough to uniquely identify someone.

If a US 5 digit zipcode is roughly equivalent to the “general area” part of a UK postcode (94107 <=> SW15) then the full UK postcode is like the 9 digit US Zip+4 format where the extra 4 digits narrow location down to a block, part of a block or even a specific building.

[marcus_holmes]

A friend of mine who lived in a tent in a park got his own postcode. True story.

Details: election time. He went to the election folks and asked for his election papers. They said "sure, where do you live?" he said "the Bender, Eastville Park, Bristol", they said "that's not a valid address", he said "that's where I live, so that's where I'd like my registration to be, please". There was some back and forth. They caved, and duly entered his address on the electoral roll as such. Then he went to the Post Office and said "this is my address, as entered on the electoral roll, can I have my postcode please?". The Post Office kinda had no option, since this was now his official address. So they gave him a postcode and the postie had to walk through the park to drop off his mail.

[gerdesj]

"A full postcode is often much less than a single street."

My business has its own unique postcode and so does next door! Between us we cover roughly three acres. Our place is one building with parking and a fair bit of greenery.

[comprev]

The concept of a postcode was originally due to the sack weight a postie could deliver before returning to the van.

Each postcode would then have an optimum delivery route often devised by the postie's themselves.

[terinjokes]

> the 9 digit US Zip+4 format where the extra 4 digits narrow location down to a block, part of a block or even a specific building.

A US Zip+4 usually identifies a specific delivery point. In some places this can mean it can even identify specific units within a building.

[neves]

Mail from a guy that wants to preserve pubs wouldn't be junk.

[philo23]

Yep, locally where I am there’s one postcode for all the houses on one side of the street (all the even numbered houses) and another for the opposite side (all the odd numbers.)

Presumably it helps a lot with validating the address is correct, kinda like a checksum, and also probably helps with how deliveries are organised by the local office before the postie is sent out with them all.

[theBobBob]

In Ireland we were very late to the postcode game and when we introduced them a few years back they actually uniquely identifies a single address. We also continued our "interesting" habit of renaming everything to make them sound more Irish so they are called Eircodes. In theory you could just put the single 7 character Eircode on a letter and it would be enough although our postal service has said we can't do that.

[lblume]

Why not?

[pjc50]

There used to be a site "postcodeine" which would overlay the prefixes onto a map as you typed, so you could enter "SW" or "KY" etc and watch it narrow down the area by keystroke.

[OJFord]

> A full postcode can narrow your location down to an individual street,

Often a single block of flats. Rurally perhaps even just a single residence?

[justincormack]

No, still usually a few residences rurally but probably more variable

[alexpotato]

I lived in SW1 many years ago and was surprised to learn, from this website, that SW goes all the way out to SW19!

[walthamstow]

Fun fact: apart from the main office SW1 they're alphabetised by area, from SW2 Brixton to SW19 Wimbledon. All of the London postcode areas are like this.

[alexfoo]

And a bit further to SW20 in Raynes Park (a.k.a. “West Wimbledon” in Estate Agent vernacular).

I’ve lived somewhere in SW18/SW15/SW19 for the last 30 years. Having not grown up in London I can’t imagine living anywhere else. Apparently many other bits of London (North, East, central, etc) are good too but I’m not ready for change.