Click the map to drop a pin.
Then drag it to fine-tune. Every format fills in at once and each one has its own copy button. Searching for a town moves the map there first, which saves a lot of scrolling.
Nothing is uploaded and nothing is stored. Close the tab and the pin is gone.
Click to place the pin, then drag it to fine-tune.
Click anywhere on the map. Or type a town into the search box and let it fly you there first.
Drag the pin. Every number updates while you move, so you can walk it along a hedge line or onto a particular roof.
Decimal degrees for software, DMS for paper, decimal minutes for a chartplotter, UTM for metres. One tap each.
Decimal degrees wins nine times out of ten. Spreadsheets take it, GeoJSON takes it, the Google Maps search box takes it, and so does every mapping library worth using. Two signed numbers, latitude first, and you’re done.
Degrees-minutes-seconds is the one you meet on paper. Deeds, aviation charts, older Ordnance Survey sheets, anything typeset before computers took over the job. It reads well out loud, which is half the reason it stuck around. One second of latitude is about 30.9 m on the ground, so whole seconds alone are a bit coarse for anything careful. Keep a decimal or two on them.
Degrees and decimal minutes looks like a compromise nobody asked for, right up until you use a marine GPS. Every NMEA sentence a chartplotter emits is in it. So is most of aviation. If someone hands you a position with a decimal point in the middle of the minutes, that’s where it came from.
Here is one point, 51.5072°N 0.1275°W, written every way this page can write it. Same spot on the pavement in all five rows.
| Format | Latitude | Longitude |
|---|---|---|
| Decimal degrees | 51.5072 | -0.1275 |
| DMS | 51°30'25.92"N | 0°07'39.00"W |
| Decimal minutes | 51°30.432'N | 0°07.650'W |
| GeoJSON order | [-0.1275, 51.5072] | |
| UTM | 30U 699338E 5710142N | |
People pad coordinates with decimals the way they pad passwords with numbers, and most of it is noise. Below is what each place is actually worth. Latitude is easy, because a degree of it is almost the same length everywhere. Longitude shrinks as you go north, which is why the second column is measured at 51.5072°N and would be wider at the equator.
| Places | Latitude step | Longitude step at 51.5072°N | Tells you |
|---|---|---|---|
| 0 | 111 km | 69 km | Which country you're in. Roughly. |
| 1 | 11 km | 6.9 km | A large city and its suburbs. |
| 2 | 1.1 km | 694 m | A town, or a stretch of motorway. |
| 3 | 111 m | 69.4 m | A neighbourhood. Good enough to meet someone in a park. |
| 4 | 11.1 m | 6.9 m | A building plot. This is where most published coordinates stop. |
| 5 | 1.1 m | 69 cm | A doorway. What a phone GPS can realistically back up. |
| 6 | 11 cm | 6.9 cm | Under a pace. Survey territory. |
| 7 | 1.1 cm | 0.7 cm | Smaller than the pin on the map, and smaller than the datum is stable. |
Five is the sensible default. Six if you’re feeding a survey. Past that you’re recording a number more precise than the ground it describes, since the tectonic plate under your feet is drifting a few centimetres a year and WGS84 quietly tracks it.
Latitude first is the convention almost everywhere a human reads the number: GPS receivers, Google Maps, Apple Maps, this page. Latitude is the north-south one, running from −90 at the South Pole to +90 at the North. Longitude runs −180 to +180, with zero through Greenwich and negative to the west.
GeoJSON flips it. So does PostGIS in most of its functions, and so does Mapbox, and so does this site’s own export. The reason is x-then-y, the order you’d write any pair of plane coordinates, and once a format picked it everything built on that format inherited it.
The tell is the 90 rule. Anything past 90 has to be a longitude, so a pair like 151.2153, -33.8568 is Sydney written the GeoJSON way. Inside 90 both readings are legal and you have to know the source. Half the “my points are in the sea off west Africa” bugs in the world are this, plus a stray zero.