Latitude & Longitude Explained β WGS84, DMS Notation, and Precision
What latitude and longitude really are, the difference between DMS and decimal degrees, accuracy by decimal places, and the WGS84 coordinate system that powers GPS.
π "37.5172, 126.9389" β do you know where these numbers point to? Latitude and longitude let you pinpoint any spot on Earth using just two numbers β a global standard coordinate system. GPS, map apps, food delivery, car navigation: every location service we use daily runs on these two numbers. This post covers the basics of latitude and longitude, the DMS vs decimal-degrees notation, accuracy by decimal places, and the WGS84 coordinate system that underlies it all.
π What Are Latitude and Longitude?
The Earth is roughly spherical, so any point on its surface can be uniquely identified by two angles.
- Latitude: The angle north(+) or south(β) of the equator (0Β°). Range: β90Β° to +90Β°.
- Longitude: The angle east(+) or west(β) of the Prime Meridian (0Β°, passing through the Royal Greenwich Observatory in England). Range: β180Β° to +180Β°.
Reference Coordinates
| Location | Latitude | Longitude |
|---|---|---|
| Equator | 0Β° | β |
| North Pole | +90Β° | β |
| South Pole | β90Β° | β |
| Prime Meridian | β | 0Β° |
| Date Line | β | Β±180Β° |
| Seoul City Hall | 37.5666Β° | 126.9784Β° |
| Tokyo Metropolitan Gov | 35.6895Β° | 139.6917Β° |
| New York Times Square | 40.7580Β° | β73.9855Β° |
Easy mnemonic: Latitude = "Y axis (vertical)", Longitude = "X axis (horizontal)". South Korea sits roughly at latitude 33β38Β° and longitude 124β131Β°.
π Notation 1: Degrees-Minutes-Seconds (DMS)
Since latitude and longitude are angles, you can express them as 1Β° = 60' (minutes) and 1' = 60" (seconds).
37Β° 31' 1.92" N, 126Β° 56' 22.20" E
37Β° 31' 1.92" N: 37 degrees, 31 minutes, 1.92 seconds north126Β° 56' 22.20" E: 126 degrees, 56 minutes, 22.20 seconds east
Pros: Traditional notation in GPS receivers, navigation, military, and aviation documents. Cons: Awkward to compute by hand (base 60), needs conversion to decimal for software.
π Notation 2: Decimal Degrees (DD)
37.5172Β°, 126.9395Β°
A single decimal number. Modern systems (Google Maps, GPS APIs, databases) almost universally use DD.
DMS β DD Conversion
DD = Degrees + Minutes/60 + Seconds/3600
Example: 37Β° 31' 1.92" β 37 + 31Γ·60 + 1.92Γ·3600 = 37.51720Β°
FindLatLng uses DD only β the "Latitude" and "Longitude" in coordinate search results are decimal degrees. So is Google Maps URLs, the Kakao Map API, and mobile GPS.
π― Precision by Decimal Places
In DD notation, the number of decimal places sets the precision. Using 1Β° latitude β 111 km:
| Decimals | Example | Lat error | Meaning / use case |
|---|---|---|---|
| 1 | 37.5Β° | ~11 km | City-level |
| 2 | 37.51Β° | ~1.1 km | District / neighborhood |
| 3 | 37.517Β° | ~111 m | Building cluster |
| 4 | 37.5172Β° | ~11 m | Building (typical GPS accuracy) |
| 5 | 37.51720Β° | ~1.1 m | Detailed location (home address, vehicle) |
| 6 | 37.517202Β° | ~11 cm | Surveying / autonomous driving (usually overkill) |
| 7 | 37.5172025Β° | ~1.1 cm | Precision surveying |
| 8+ | 37.51720253Β° | < 1 cm | RTK GPS (military / surveying only) |
Typical decimal places by system
- Google Maps URLs: 7 digits (e.g., 37.5172025)
- Kakao Map API: 6β7 digits
- Consumer mobile GPS: 5β6 digits (real-world accuracy ceiling ~5 m)
- Database geo column: 6β8 digits (storage standard)
- User input / sharing: 4β6 digits is plenty (error under ~10 m)
Excessive precision is meaningless: If your phone's GPS is accurate to Β±5 m, storing 8 decimals (Β±1 mm) just records noise below the 7th digit. 6 digits is enough for general services.
π What Is WGS84, Then?
Latitude and longitude alone are abstract angles. The coordinate reference system defines what those angles are measured relative to.
WGS84 (World Geodetic System 1984)
- A global standard geodetic system defined by the U.S. Department of Defense in 1984 for GPS
- Models the Earth as a reference ellipsoid (semi-major axis 6,378,137 m, flattening 1/298.257223563)
- GPS satellites broadcast coordinates in WGS84
- Google Maps, Apple Maps, OpenStreetMap, Kakao Map, Naver Map β virtually every modern map service uses WGS84
Are There Other Coordinate Systems?
| System | Use case |
|---|---|
| WGS84 (EPSG:4326) | Global standard (maps, GPS) β used 99% of the time |
| Web Mercator (EPSG:3857) | Google Maps display tiles |
| TM Central Origin (EPSG:5186) | Korean national surveying (cadastral, urban planning) |
| UTM 52N | Korean military / aviation |
| KATEC | Older Korean GIS / some legacy navigation |
For most users, WGS84 is all you need to know. FindLatLng returns coordinates in WGS84 (EPSG:4326). Converting to other systems requires GIS tools (QGIS, proj4, etc.).
π¬ FAQ
Q. Latitude or longitude first?
Map coordinates are typically written "latitude, longitude" (e.g., 37.5172, 126.9389). Google Maps @lat,lng,... URLs follow this.
GeoJSON and some GIS standards use the opposite order β [longitude, latitude] β so be careful.
Q. What about negative coordinates?
- Negative latitude: Southern Hemisphere (Sydney β33.86Β°, Rio de Janeiro β22.91Β°)
- Negative longitude: West of the Prime Meridian (New York β73.99Β°, Los Angeles β118.24Β°)
Q. Why is Korea at longitude 124β131Β°? Korea sits in East Asia, about 130Β° east of the Prime Meridian (England). Japan ranges 130β146Β°, China spans 73β135Β°.
Q. Is 1Β° always 111 km?1Β° latitude is always ~111 km anywhere (Earth's circumference 40,007 km Γ· 360Β°). 1Β° longitude varies with latitude: ~111 km at the equator, ~55.5 km at 60Β° latitude, 0 km at the poles. At 37.5Β° (Seoul), it's about 88 km.
π Wrap-Up
- Latitude/longitude = a global standard for pinpointing any spot on Earth
- Two notations: DMS (
37Β° 31' 1.92") and DD (37.5172) β modern systems use DD - Decimal places set the precision: 6 digits is plenty for general services
- WGS84 = effectively the only standard for GPS and maps (EPSG:4326)
- Other systems (TM, UTM, KATEC) appear mostly in surveying and government
Convert addresses to coordinates, or pick a point on the map! FindLatLng β Lat/Lng Finder β