Paste anything that looks like a coordinate.
Degree signs, primes, smart quotes pasted out of a PDF, colons from a sexagesimal clock format, the odd stray word. It gets stripped and read.
Or click the map, and the box fills in for you.
Click or drag to fill the box from the map.
Every coordinate on this page is the same two angles underneath. All that changes is how the fraction gets written down, and that choice is historical rather than technical. Sixty minutes to a degree, sixty seconds to a minute: Babylonian arithmetic, still in use because clocks and charts both inherited it.
Decimal degrees is the one software wants. Signed, so a minus does the work of S or W. Sorts correctly, subtracts correctly, survives a trip through a spreadsheet.
Degrees-minutes-seconds is the one on paper and the one people say out loud. It’s also the one that quietly loses metres when someone prints it without decimals on the seconds.
Degrees and decimal minutes splits the difference and dominates at sea. Open the NMEA stream from any chartplotter and that’s what’s in it. Aviation too.
The Opera House, 33.8568°S 151.2153°E, written four ways:
| Format | Latitude | Longitude |
|---|---|---|
| Decimal degrees | -33.8568 | 151.2153 |
| DMS | 33°51'24.48"S | 151°12'55.08"E |
| Decimal minutes | 33°51.408'S | 151°12.918'E |
| UTM | 56H 334901E 6252289N | |
Real coordinates arrive filthy. Copied out of a PDF with curly quotes standing in for primes, or out of an email where the degree sign became a masculine ordinal, or out of a logger that writes colons. The parser throws away punctuation, keeps digits, signs and the four hemisphere letters, then works out where one angle ends and the next begins.
That last part is the tricky bit. 40 26 46 is one angle in three pieces. 40.44 -79.98 is two angles. The rule: degrees and minutes have to be whole when something follows them, so a decimal point ends the angle. A sign ends it. A hemisphere letter ends it. A comma ends it, unless honouring the comma would leave more than two angles, in which case it gets ignored and you can write 40, 26, 46 N after all.
Every row below was run through the parser when this page was rendered.
| You type | You get |
|---|---|
| 40°26'46"N 79°58'56"W | 40.4461, -79.9822 |
| 40 26 46 N, 79 58 56 W | 40.4461, -79.9822 |
| 40.4461, -79.9822 | 40.4461, -79.9822 |
| N 40° 26.767', W 79° 58.933' | 40.4461, -79.9822 |
| 40:26:46N 79:58:56W | 40.4461, -79.9822 |
| -33.8568 151.2153 | -33.8568, 151.2153 |
| 151.2153, -33.8568 | -33.8568, 151.2153 (swapped) |
| lat 51.5072 lon -0.1275 | 51.5072, -0.1275 |
Converting between these formats is exact. The same angle goes in and comes out; no projection, no datum, no approximation. What costs you is the printing, and it costs more than people expect. One second of latitude is about 30.8 m, so DMS rounded to whole seconds can only ever tell you which half of a tennis court you’re on.
| Rounded to | Worst case, north–south | Comment |
|---|---|---|
| DMS, whole seconds | 15.4 m | The usual way DMS is printed. |
| DMS, two decimals on the seconds | 15 cm | What this page outputs. |
| Decimal minutes, three decimals | 92 cm | The NMEA default off a chartplotter. |
| Decimal minutes, whole minutes | 924 m | Fine at sea. Hopeless on land. |
| Decimal degrees, four places | 5.5 m | The most common way coordinates get published. |
| Decimal degrees, six places | 5.5 cm | What this page outputs. |
East-west error is the same or smaller, shrinking with the cosine of the latitude, so the figures above are the pessimistic ones. Worth knowing if you’re copying a DMS position off a document and wondering why it lands in the wrong garden. The document rounded, and 15.4 m of slop is about the width of a house.
Output here keeps two decimals on the seconds and three on the minutes, which puts the rounding well under the error of any GPS you own. Copy fewer digits if you like. Just don’t copy fewer and then treat the result as a survey mark.