Why what3words beats GPS for lost luggage

The three-word address concept

what3words is a global addressing system that divides the surface of the earth into a grid of 3-metre by 3-metre squares and gives each one a unique three-word identifier. Every square on the planet — including in oceans, parks, and the middle of an airport apron — has its own combination of three words.

You can look up any address at what3words.com. The square that BagBeacon’s homepage uses as a sample is ///filled.count.soap— click through and you’ll see exactly the patch of London it points at.

The trick is that ordinary words are dramatically easier to communicate over a phone than digits. “Filled, count, soap” is unambiguous, easy to repeat, and easy to write down. “Fifty-one point five oh seven four, minus zero point one two seven eight” is none of those things.

The error-margin problem with GPS

Latitude and longitude are precise to whatever level of decimal places you’re given. Six decimal places gets you down to about 10 centimetres. The trouble is that humans aren’t good at copying long strings of digits over a phone, and the error you introduce by mistyping one digit gets bigger the closer to the start of the number you make the mistake.

Some rough numbers, in central London (around lat 51.5, long −0.1):

• Mistype the first decimalof latitude and you’ve moved roughly 11 km— from Westminster to Wandsworth.
• Mistype the third decimaland you’ve moved roughly 110 metres— from one side of Trafalgar Square to the other.
• Mistype the fifth decimaland you’ve moved about 1 metre— still in the same room, but you might be looking at the wrong table.

By contrast, what3words has the property that adjacent squares almost never have similar-sounding words. The system is designed so that ///filled.count.soap is many kilometres away from ///fillet.count.soap. A single mistyped word produces an obviously wrong location, not a slightly wrong one. Errors fail loudly, which is what you want when you’re recovering a bag.

A real-world example

Imagine you’ve flown to a city you don’t know. Your suitcase is missing. The hotel concierge texts you that they’ve found a bag matching your description in the lost-property cupboard.

With GPS:they read out the lobby’s latitude and longitude from their phone. You write it down, type it into Google Maps, and end up looking at a roughly correct district. You confirm the hotel name and head over — the coordinate didn’t actually add anything that the hotel’s address didn’t already give you.

With what3words:they tap a button that shares the three-word address for the exact spot they’re standing — not just the building. You see ///filled.count.soap land in your phone alongside a Google Maps link. You can tell, before you set off, that the bag is in the lobby rather than in a back office two floors up. When you arrive, you can ask reception “is the bag at ///filled.count.soap?” and someone who wasn’t there for the original conversation can find it anyway.

The difference matters most when the building is large — an airport, a station, a conference centre, a campus. “Heathrow” is a lot of square metres. A three-word address narrows it to one of them.

Why BagBeacon uses what3words

Every BagBeacon scan that includes a location resolves to a what3words address as well as a Google Maps link. We send both in the SMS and email alert. The Google Maps link is the universal fallback — it works in any browser, no apps required. The what3words address is for the human handover: it’s the part you can read aloud over a phone, write on a post-it, or compare across two people looking at different screens.

When a finder taps “Help reunite us” on a scanned BagBeacon, their browser asks for their location with the standard W3C geolocation prompt. If they consent, we resolve the latitude and longitude into a what3words square at the moment the alert is sent — so the address you see is the precise spot the finder was standing when they tapped, accurate to about 10 metres.

Where what3words is weaker

We should be honest. what3words isn’t universally better than GPS — it’s better for one specific job. The cases where GPS still wins:

• Machine-to-machine pipelines.If you’re feeding location data into a logistics system, a delivery API or a mapping algorithm, you want raw coordinates. Word addresses are for humans.
• Open-data interoperability.Latitude and longitude are an international standard with no licence. what3words is a proprietary system — the algorithm and word list are owned and licensed by what3words Ltd. If you need a guaranteed-forever, royalty-free location format, GPS coordinates win.
• Multilingual environments. what3words has addresses in over 60 languages, but each address is language-specific (the English square is different from the French square). For an English-speaking finder communicating with an English-speaking owner, this is fine; for a more complicated chain it can introduce friction.
• Dependence on a private service.If the what3words API becomes unavailable, the address itself is meaningless without the lookup. We mitigate this by sending Google Maps links alongside — so you have a fallback — but it’s a real consideration.

The verdict

Use what3words when a person is going to read, speak, or write the location.Recovering lost luggage. Meeting in a park. Telling an ambulance which entrance to come to. Telling someone where in a large building you’re standing. The whole point of word addresses is that they survive the trip from one phone, through a human voice or hand, to another phone — with errors that fail loudly rather than quietly.

Use GPS coordinates when a machine is going to read the location. Logistics pipelines, mapping APIs, geofencing rules, GIS tools, anywhere you need an open standard with no licensing or third-party dependency.

For BagBeacon, we send both. The Google Maps link is the universal fallback that works anywhere; the what3words address is the part that helps the actual humans on both ends of the recovery talk to each other.