Understanding Coordinate Systems in Geographic Data
Learn about coordinate reference systems (CRS), projections, and how they affect your geographic data conversions.
What are Coordinate Systems?
A coordinate system is a framework that defines how locations on Earth are represented as coordinates. Every geographic dataset uses a coordinate reference system (CRS) to specify where features are located in relation to the Earth's surface.
Why This Matters: Using the wrong coordinate system can cause your data to appear in the wrong location, be distorted, or not align with other datasets.
Most Common Coordinate Systems
WGS84 (EPSG:4326)
The most widely used geographic coordinate system. Uses latitude and longitude in decimal degrees.
- GPS devices
- Google Maps
- Most web mapping services
- GeoJSON (default)
- Longitude: -180° to +180°
- Latitude: -90° to +90°
- Example: -122.4194, 37.7749
Web Mercator (EPSG:3857)
Projected coordinate system used by most web mapping applications. Optimized for web display.
- Google Maps
- OpenStreetMap
- Bing Maps
- Most web map tiles
- Units: Meters
- Origin: Equator and Prime Meridian
- Example: -13627851, 4544803
UTM (Universal Transverse Mercator)
A family of projected coordinate systems that divide the world into 60 zones, each 6° wide.
- Surveying and engineering
- Military applications
- Scientific research
- High-precision mapping
- Units: Meters
- 60 zones worldwide
- Example: UTM Zone 10N
Geographic vs Projected Coordinate Systems
Geographic (Unprojected)
- • Uses latitude and longitude
- • Measured in degrees
- • Represents locations on Earth's curved surface
- • Good for global datasets
- • Example: WGS84 (EPSG:4326)
Projected
- • Uses X,Y coordinates
- • Measured in linear units (meters, feet)
- • Flattens Earth's surface onto a plane
- • Good for local/regional analysis
- • Example: UTM, State Plane
Common Coordinate System Issues
Data Appears in Wrong Location
Usually caused by incorrect CRS assumption. Check if your data is in WGS84 or a projected system.
Datasets Don't Align
Different coordinate systems prevent proper overlay. Transform all data to the same CRS.
Distorted Shapes
Projection distortion affects shape, area, or distance. Choose appropriate projection for your region.
Best Practices
When Converting Data:
- • Always identify the source CRS
- • Choose appropriate target CRS
- • Document CRS information
- • Test converted data for accuracy
- • Keep original data as backup
Format Recommendations:
- • Web maps: WGS84 (EPSG:4326)
- • Analysis: Appropriate UTM zone
- • Global data: WGS84
- • Local surveys: Local projected CRS
- • Web tiles: Web Mercator (EPSG:3857)
Need Help with Coordinate Systems?
Our converter automatically handles common coordinate system transformations. Most web formats use WGS84 by default.