Coordinates Converter
Convert latitude and longitude between decimal degrees, DMS and degrees-decimal-minutes.
Every notation
| Format | Value |
|---|---|
| Decimal degrees | 51.477928, -0.001545 |
| Degrees minutes seconds | 51° 28′ 40.54″ N, 0° 0′ 5.56″ W |
| Degrees decimal minutes | 51° 28.6757′ N, 0° 0.0927′ W |
| Signed decimal | 51.477928 / -0.001545 |
Ground precision at this latitude
| Precision | Latitude | Longitude |
|---|---|---|
| 1 decimal place | 11,125.74 m | 6,947.41 m |
| 2 decimal places | 1,112.57 m | 694.74 m |
| 3 decimal places | 111.26 m | 69.47 m |
| 4 decimal places | 11.13 m | 6.95 m |
| 5 decimal places | 1.11 m | 0.69 m |
| 6 decimal places | 0.11 m | 0.07 m |
Three ways to write the same point
- DD — decimal degrees,
51.477928, -0.001545. What GPS devices, mapping APIs and spreadsheets use. - DMS — degrees, minutes, seconds,
51° 28′ 40.5″ N. Traditional, still standard on printed charts. - DDM — degrees and decimal minutes,
51° 28.6757′ N. The marine and aviation convention, because one minute of latitude is one nautical mile.
decimal = degrees + minutes/60 + seconds/3600
Signs versus hemispheres
Decimal notation puts the hemisphere in the sign — north and east positive,
south and west negative. DMS uses a letter instead. Mixing the two conventions is
the most common coordinate error there is: writing
-33° 52′ 05″ S negates twice and lands you in the
northern hemisphere.
Only the degrees carry the sign. Minutes and seconds are always positive.
How many decimals you need
Latitude precision is nearly constant, but a degree of longitude shrinks with the cosine of the latitude — from 111 km at the equator to zero at the poles. The table above is calculated for your actual latitude rather than a global average.
As a rule: 4 decimal places locates a building, 5 locates a doorway, and 6 is finer than consumer GPS can actually resolve. Anything beyond 7 is noise.
These conversions assume the same datum throughout. Coordinates in WGS 84 (what GPS uses) can differ from a local national grid by tens or even hundreds of metres, and no notation change will fix that.