Latitude and Longitude: How GPS Coordinates Actually Work
Every location on Earth can be described by two numbers: latitude and longitude. Here's what those numbers mean, why there are different formats, and how to use them.
How Precise Are GPS Coordinates?
The number of decimal places in a coordinate directly determines its real-world precision:
| Decimal Places | Precision | Real-World Example |
|---|---|---|
| 0 (40, -74) | ~111 km | Wrong city |
| 1 (40.7, -74.0) | ~11 km | Wrong neighborhood |
| 2 (40.71, -74.01) | ~1.1 km | Correct neighborhood |
| 3 (40.713, -74.006) | ~111 m | Correct city block |
| 4 (40.7128, -74.0060) | ~11 m | Individual building |
| 5 (40.71278, -74.00597) | ~1.1 m | Individual room |
| 6 (40.712776, -74.005974) | ~0.11 m | Survey point (centimeter) |
For most practical purposes, 5-6 decimal places provide survey-grade precision. Storing more than 8 decimal places is rarely meaningful since consumer GPS devices have an accuracy of only 3-5 meters. See our full Decimal Precision Guide for details.
Finding GPS Coordinates
On Your Phone
Google Maps (Android/iOS): Long-press any spot on the map. The coordinates appear at the top of the screen in decimal degrees format.
Apple Maps (iOS): Drop a pin, then tap the pin label. Coordinates show at the bottom of the info card.
On Your Computer
Google Maps: Right-click any point and select "What's here?" The coordinates appear at the bottom in a popup.
From an Address
Type the address into Google Maps and long-press/right-click the marker to get precise coordinates.
The Positive/Negative Convention
Coordinates can be written with compass directions (N, S, E, W) or with positive/negative signs. The convention is:
- North latitude = positive: 40.71 or 40.71N
- South latitude = negative: -33.87 or 33.87S
- East longitude = positive: 139.69 or 139.69E
- West longitude = negative: -74.01 or 74.01W