Grid reference vs What3Words vs lat/long
There are three common ways to describe a location in Britain. Each has strengths, and the right choice depends on who you’re telling and what they’ll use it for.
| Grid reference | Lat/long | What3Words | |
|---|---|---|---|
| Example | SH 6098 5437 | 53.06847, -4.07622 | three words |
| Coverage | Great Britain only | Whole world | Whole world |
| Works on a paper map | Yes, printed on every British map | Rarely, needs margin scales | No |
| Precision | You choose: 1 km to 1 m | Set by decimal places | Fixed 3 m square |
| Works without an app or internet | Yes | Yes | Needs the company’s app or website to decode |
| Open standard | Yes | Yes | No, proprietary |
Grid references
Grid references are the standard for walking, climbing, mountain rescue, surveying and the Duke of Edinburgh’s Award, because every British map is printed with the grid. You can read one with nothing but a map, and its length tells you how precise it is. The downside is that it only works in Great Britain. Ireland uses its own grid.
Latitude and longitude
Lat/long is the global standard and what GPS works in natively, so it’s the right choice for sharing with apps, sailors, pilots or anyone outside Britain. Two cautions:
- Formats vary. The same place can be written in decimal degrees (53.06847) or degrees, minutes and seconds (53° 04′ 06.5″). Mixing them up causes big errors.
- Datums differ. GPS uses WGS84, while older British maps printed lat/long on the OSGB36 datum. The two can differ by more than 100 m in Britain. Converters such as this one handle the shift for you.
What3Words
What3Words gives every 3 m square in the world a unique three-word name. Words are easy to say over a bad phone line, and many emergency control rooms accept them. However, the system is owned by a private company, the words can only be turned back into a location with its software, and similar-sounding addresses can occasionally point to the wrong place. If you give a What3Words address in an emergency, a grid reference or lat/long alongside it gives the responder a second check.
Which should I use?
- Outdoors in Britain, or talking to mountain rescue: a grid reference.
- Sharing with an app, a boat or someone abroad: latitude and longitude.
- When the person you’re telling asks for it: whatever they ask for. You can convert between grid references and lat/long on the converter.