EPSG Coordinate Conversion Guide
Convert coordinates between EPSG:4326, Web Mercator (EPSG:3857), and Korean coordinate systems EPSG:5173–5188 with proj4. Both single coordinates and batch CSV conversion run in the browser.
Follow the field labels for longitude and latitude order. Choosing the wrong axis order or source CRS can produce a valid calculation at the wrong real-world location.
Frequently asked questions
What's the difference between EPSG:4326 and EPSG:3857?
EPSG:4326 (WGS84) is longitude/latitude in degrees, used by GPS and most APIs. EPSG:3857 (Web Mercator) is a projected CRS in meters used by web map tiles; it distorts area and shouldn't be used for area or distance math.
Should I use EPSG:5174 or EPSG:5179 for Korean data?
EPSG:5174 (Bessel 1841) is the legacy CRS in older cadastral data; EPSG:5179 (GRS80/Korea 2000, "UTM-K") is the modern one Kakao, Naver, and VWorld use today.