Decimal degrees (DD) express latitude and longitude as decimal fractions of a degree. They are common in GIS and web mapping applications. Positive latitudes are north of the equator and negative ones are south. Positive longitudes are east of the prime meridian and negative ones are west.
Precision by decimal place
| Decimal place | Approx. precision |
|---|---|
| 0.1° | 11 km |
| 0.01° | 1.1 km |
| 0.001° | 110 m |
| 0.0001° | 11 m |
| 0.00001° | 1.1 m |
| 0.000001° | 0.11 m |
Both notations remain common. Accuracy suffers if you round too soon.