Eircode: Perfect, Broken, Or In-Between?

This may be a bit of a weird post to write, seven years after leaving Ireland, and now that i’m a British citizen, but since it came up on Threads, and I thought this is a good opportunity to discuss the fact that people want to “take a side” in the strangest of situations, and appear to be unable to appreciate that what they see from their point of view is not necessarily the full picture.

So first of all, what are we talking about? Eircode is Ireland’s first postcode system, and was introduced in 2014. At first sight, they might look very similar to the British postcodes that were fully introduced 40 years before that, but make no mistakes: the two systems are different, not interoperable, and do not follow the same design requirements at all. And that’s where it all started: when a friend compared the two, enthusiastically pointing out you only need the Eircode to address mail in Ireland — and that is not quite true. But good luck trying to explain the nuance to those who expect Eircode to be a perfect system.

It’s also important to note that I arrived in Ireland before Eircode were a thing — so I have seen first hand the slight mess of trying to provide an Irish address to systems that believe falsehoods and expect a postcode to exist for any address. I personally got bitten by this twice: the first time, when I transferred my domains from OVH with my Italian address to Gandi with my Irish address (between Gandi’s and eurID’s systems there was some incompatibility on how they expected to provide an address for Ireland in particular, at that point the only EU country without a compatible postcode system), and the second time with TransferWise (now Wise), once they introduced their “borderless accounts”, and force-verified all addresses… forgetting that not every address has a postcode — after unblocking my account they admitted it was “a specific problem affecting Irish addresses” — they laughed, and admitted that was the problem, when I pointed out that Ireland is not the only country without postcodes.

Which means Eircode was a significant improvement for Irish residents when dealing with international systems that have been struggling with accepting a country that in the 21st century still lacked postcodes. Though when it was rolled in, I remember a lot of complains from locals: some of it was general change resistance, some of it a bit more complicated, particularly for Dublin. Dublin already had postal towns identifiers, numbered from 1 onwards, with odd numbers North of the Liffey, and even numbers on that South side, with Dublin 4 being where Silicon Docks used to be located — these were mostly replaced with Eircodes using a similar format (D04 xxx for Dublin 4 addresses), but some houses found themselves being issued an Eircode with a higher number than they expected, which turned out to affect property prices. I’m not going to try to understand or justify this whole topic because I have some rarely shared opinions about property prices.

Now though, trying to explain that Eircode and the British postcodes take different trade-offs, appeared to just summon defenders of the Eircode system, which I find both surprising and disappointing. So let me try to discuss some of the differences in tradeoffs.

Eircode are very specifically about delivering. This might sound obvious but people don’t always seem to get what this means, as seen by the amount of people who seem to think that there is a single Eircode per building — indeed, there isn’t. There is a single Eircode per deliverable address, as explained on the Eircode website. Multiple buildings within a single campus do not get their own Eircode, if all of the mail and deliveries go through the same loading dock. Similarly, if a house is converted to individual flats, but they do not get separate mailboxes (which was fairly common in Dublin South), there is a single Eircode for all of those flats. On the other hand, if a purpose built apartment building has individual mailbox for each flat, each one of them gets their own independent Eircode.

This makes Eircode both more fine grained (one-per-mailbox) and less so (some buildings not having a code at all, particularly before they are fully completed and open) than the British postcode system. While the latter was originally introduced for mail delivery only, by now it is used for so many other things that make these trade-offs very much incompatible. But it make sense in Ireland, a country that is vastly rural, where buildings might not actually have a street name, let alone a number.

What follows from this is an Eircode is not necessarily enough to completely route a delivery to the right person. While it does work for a number of people, who live in a house or flat with their own mailbox, there will be individuals and businesses who, to get their mail, require a full address. If it works for you to receive mail with just an Eircode, I’m glad for you — but do not push for forms to drop everything but the Eircode, and if you’re a programmer, don’t expect others to live in the same reality!

You may also want to make it easier on your postie too — most mailboxes don’t have their Eircode printed on, but rather a house or flat number. While delivery companies are going to have to decode the Eircode into an address anyway, it’s much easier for the delivery person to match the written address with what is visible, rather than have to consult some other source to find out that “Yes, this should be put into the mailbox of flat number 8.”

This is not anything particularly special about Eircode itself, by the way. Back when I lived in Dublin, Luca (lu_zero) sent me a postcard from Tokyo, addressed as “flameeyes@ — Google — Ireland” and within a few days it was on my inbox tray. I nearly tried sending myself a postcard without including the country, and see whether it would be inter-office’d to me, but I decided against that.

Aside: yes, my username at work was (and is!) flameeyes@ — don’t let anyone tell you that just because you join a big company you need to get on with the program and drop your favourite alias. I’m currently working to make Flameeyes part of my legal name, but even before that, most people at work don’t even know my “real” last name!

Most importantly, and something that people seem to miss entirely, is that Eircode is not geographically arranged. Only the first part of the code (e.g. D04) is geographically linked, and even that is not really following a size progression, like the British post code does. In the British system, N, N1, N1C become progressively smaller areas — whereas Eircodes for D12 and D11 are on opposite sides of Dublin — D0 and D1 by themselves are not useful to restrict an area at all.

This is the part that, to me, makes the less sense. Since the second part of Eircode is arbitrarily generated, there is no way to quickly spot two postcodes that are near each other — unlike N1C 4AG and N1C 4AA which are walking distance, or in my development, where most building share the same five digits of the postcode.

This means very little for most people, but for logistics companies it makes a ton of difference: you cannot tell from Eircode alone which parcels go to the same building, as the second part of the address is not sequential, so what you end up having to do is to decode the Eircode into a location, then apply a different geocoding to provide a more reasonable bucketing so that all parcels going to the same route are packed together.

And yet, Eircode is a lot more specific than most other postcodes, because the Eircode website, as well as Google and Apple maps nowadays, allow you to decode an Eircode into a full address. For many this is obviously not a bad thing, but it breaks the expectations from many systems, that a postcode is not PII, since it’s just part of an address. Which is why credit card companies consider a postcode confirmation a lower tier confirmation than full address — which make no sense with Eircode.

«But I know that the code is specific to my home, so of course I don’t go around yelling it left and right!» Fine, but Eircode broke the expectations of the rest of the world. Say that a streamer is doing a “received mail” segment, and decides to hide all the details from return labels except for a vague location for tracking where they are receiving them from — do you expect them to know that those six digits at the bottom actually encode everything else on the address, and be enough to go and stalk the person?

Whereas I can feel free to share that I live in London TW8 — it’s a much smaller area than D04, but at the same time it’s not specific enough that I wouldn’t want to share that in public. I could even give you the full post code for my building and you still wouldn’t be able to find my flat (short of passing through the concierge without an invitation, and walking the full building to find my WiFi.)

These are all different trade-offs — some of which will become likely less awkward in the long run. For example, maybe by now it is getting common to put the Eircode on a label next to the mailbox, it wasn’t when I lived there, so that would make it easier on posties and delivery people. And I do believe that the more rural-focused nature of Eircode is the correct choice for Ireland.

But I also believe it is very important to be able to have good discussions in terms of pros and cons of various solutions, because I have very rarely found a solution that is superior to all others with no weak points — it is much more common to have a solution that is the worst of all options, but that’s a different story.