Coordinate Systems Guide
This page provides a comprehensive overview of all 39+ coordinate systems and geodetic datums supported by LatLong Converter. Each coordinate system includes its definition, development history, typical applications, unique features, and ellipsoid parameters. Use this guide to understand the characteristics of each system and choose the right one for your GIS, surveying, or mapping needs.
Global Systems
Global coordinate reference systems used worldwide for GPS, satellite navigation, international mapping, and military operations.
WGS84 (World Geodetic System 1984) is the global standard geodetic reference system used by GPS. It defines an Earth-centered, Earth-fixed coordinate system and geodetic datum.
- GPS Compatibility: WGS84 is the native coordinate system of the Global Positioning System (GPS), ensuring direct compatibility with all GPS receivers and satellite navigation systems worldwide.
- Global Standard: As the most widely adopted geodetic datum, WGS84 provides a consistent global reference frame for mapping, surveying, and geospatial data exchange across international boundaries.
- High Precision: With continuous refinements, WGS84 achieves centimeter-level accuracy globally, making it suitable for high-precision applications like surveying, drone navigation, and scientific research.
UTM (Universal Transverse Mercator) is a map projection system that divides the Earth into 60 zones, each 6 degrees of longitude wide.
- 60 Zones: The Earth is divided into 60 north-south zones, each spanning 6 degrees of longitude.
- Metric System: UTM uses meters as its unit of measurement, with easting and northing coordinates.
- Minimal Distortion: Each zone limits distortion to less than 0.1% within the zone boundaries.
MGRS (Military Grid Reference System) is a global grid reference system based on UTM projections. It divides the Earth into 60 UTM zones and uses grid zone designators and 100km square identifiers for precise location referencing.
- UTM-based Grid: MGRS is built on the UTM projection system, dividing the Earth into 60 zones of 6° longitude each, with additional grid zone designators for latitude bands.
- High Precision: MGRS can represent locations with varying precision levels from 10km down to 1 meter, making it suitable for both strategic planning and tactical operations.
- International Standard: MGRS is the standard military grid system for all NATO countries, ensuring interoperability across allied forces and international emergency response teams.
Chinese Systems
National coordinate systems used in China for official surveying, mapping, and commercial map services.
GCJ-02 (Mars Coordinate System) is a geodetic datum used in China for geospatial data. It applies an encrypted offset to WGS84 coordinates to comply with national regulations.
- Encrypted Offset: GCJ-02 applies a non-linear offset algorithm to WGS84 coordinates, shifting positions by up to several hundred meters. The exact algorithm is classified by the Chinese government.
- China Region Only: The encryption offset only applies within mainland China. Coordinates outside China pass through without modification.
- Industry Standard: GCJ-02 is the mandatory coordinate system for all commercial map services operating in China. Converting between WGS84 and GCJ-02 is essential for international data integration.
BD-09 (Baidu Coordinate System) is a geodetic system developed by Baidu, based on GCJ-02 with additional encryption for use in Baidu Maps and related services.
- Double Encryption: BD-09 adds a second encryption layer on top of GCJ-02, making it the most heavily obfuscated coordinate system used in China.
- Baidu Ecosystem: Used exclusively within Baidu's mapping platform. If you're developing with Baidu Maps API, all coordinates must be in BD-09 format.
- Third-party Conversion: Conversion between BD-09 and other systems relies on reverse-engineered algorithms that provide sub-meter accuracy.
CGCS2000 (China Geodetic Coordinate System 2000) is China's official national geodetic coordinate system, replacing Beijing 1954 and Xian 1980 systems. It is aligned with ITRF97.
- ITRF Alignment: CGCS2000 is aligned with the International Terrestrial Reference Frame 1997 (ITRF97) at epoch 2000.0.
- WGS84 Compatibility: CGCS2000 and WGS84 are essentially identical for most practical applications, with differences typically less than 1 meter.
- Modern Infrastructure: CGCS2000 is supported by a nationwide network of continuously operating reference stations (CORS) across China.
BJ54 (Beijing 1954 Coordinate System) was China's first national geodetic coordinate system.
- Krasovsky Ellipsoid: BJ54 uses the Krasovsky 1940 ellipsoid, which differs from WGS84 by approximately 100-200 meters.
- Legacy System: While largely superseded by CGCS2000, BJ54 coordinates exist in vast archives of historical maps.
BJ2000 is China's modern geodetic reference system based on CGCS2000, established to replace BJ54.
- CGCS2000 Compatibility: BJ2000 uses the same reference ellipsoid as CGCS2000.
- 7-Parameter Required: Converting between BJ2000 and WGS84 requires regional 7-parameter values.
Xi'an 80 (Xian1980, Chinese Geodetic Datum 1980) is a Chinese national geodetic datum established in the 1980s. It uses the IAG75 ellipsoid (a=6378140m, 1/f=298.257) and employs a 7-parameter Helmert transformation from WGS84. It is widely used in Chinese surveying and mapping alongside BJ54 and CGCS2000.
- Chinese National Standard: Xi'an 80 is an official Chinese national geodetic datum, used extensively in legacy surveying, mapping, and infrastructure data.
- IAG75 Ellipsoid: Xi'an 80 uses the IAG75 ellipsoid (a=6378140m, 1/f=298.257), the same as the IUGG 1975/IAU 1976 recommended values.
North American Systems
Official geodetic datums for the United States, Canada, Mexico, and Central America used in federal and state mapping.
NAD27 (North American Datum 1927) is a historic geodetic datum for the United States, Canada, and Mexico, based on the Clarke 1866 ellipsoid. It was the primary reference system for North American mapping for most of the 20th century.
- Historical North American Standard: NAD27 was the primary geodetic datum for North America for over 50 years, used for all USGS topographic mapping, state plane coordinates, and aviation charts.
- Clarke 1866 Ellipsoid: NAD27 uses the Clarke 1866 ellipsoid (a=6378206.4m), optimized for the North American continent during the 19th century but differing from modern global ellipsoids by 100-200 meters.
- Legacy Data Support: Millions of historical maps, property records, and scientific datasets use NAD27 coordinates. Converting legacy NAD27 data to modern systems is essential for GIS integration.
NAD83 (North American Datum 1983) is the official geodetic reference system for the United States, Canada, Mexico, and Central America. It uses the GRS80 ellipsoid and is aligned with ITRF for North American plate stability.
- North American Standard: NAD83 is the legal coordinate system for the United States and Canada, used by federal agencies including USGS, NOAA, and state governments for all official mapping and surveying.
- GRS80 Ellipsoid: NAD83 uses the GRS80 ellipsoid (a=6378137m), the same reference ellipsoid used by WGS84, making conversion between the two systems virtually transparent for most applications.
- Multiple Realizations: NAD83 has been refined through multiple realizations (1986, NSRS2007, 2011) to incorporate improved GPS measurements and crustal motion models, with sub-meter alignment to ITRF.
European Systems
Geodetic reference systems for European countries used in pan-European GIS, national mapping, and cross-border infrastructure.
OSGB36 (Ordnance Survey Great Britain 1936) is the official geodetic datum for England, Scotland, Wales, and Northern Ireland. It uses the Airy 1830 ellipsoid and is the basis for all UK Ordnance Survey mapping.
- UK National Standard: OSGB36 is the official geodetic datum for the United Kingdom, used by the Ordnance Survey for all national mapping products and by government agencies for land and property records.
- Airy 1830 Ellipsoid: OSGB36 uses the Airy 1830 ellipsoid (a=6377563.396m, 1/f=299.3249646), which was specifically optimized for the British Isles, providing superior accuracy for UK-based measurements compared to global ellipsoids.
- British National Grid Base: OSGB36 serves as the geographic coordinate basis for the British National Grid (BNG) projection, the standard grid system for all UK mapping from large-scale urban plans to small-scale road maps.
ETRS89 is the EU-recommended geodetic reference system for Europe, fixed to the stable part of the Eurasian Plate.
- Plate-fixed Reference: ETRS89 is fixed to the Eurasian tectonic plate, meaning coordinates of European landmarks remain stable over time.
- EU Standard: ETRS89 is recommended by the European Commission for all geographic data under the INSPIRE directive.
- WGS84 Compatibility: For most practical applications, ETRS89 and WGS84 coordinates differ by less than 1 meter within Europe.
ED50 was the primary geodetic reference system for Western Europe during the mid-20th century.
- Historical European Standard: ED50 served as the common geodetic reference for Western Europe for decades.
- Hayford Ellipsoid: ED50 uses the International Ellipsoid 1924, which differs significantly from modern ellipsoids.
HTRS96 is Croatia's national geodetic reference system, based on ITRF96 and compatible with ETRS89.
- ETRS89 Compatibility: HTRS96 coordinates are very close to ETRS89, enabling seamless data exchange.
- GRS80 Ellipsoid: Uses the modern GRS80 ellipsoid, providing excellent GPS compatibility.
EOV is Hungary's national unified projection coordinate system, used for GIS, mapping, and cadastral surveys.
- National Projection: EOV is a plane coordinate system specific to Hungary, using easting and northing values in meters.
- Modified Gauss-Kruger: EOV uses a modified Gauss-Kruger projection with a central meridian at 19 deg E.
CH1903+ (Swiss Geodetic Datum 1903+) is the official geodetic datum for Switzerland and Liechtenstein. It uses the Bessel 1841 ellipsoid with a 3-parameter shift (dx=674.4m, dy=15.1m, dz=405.3m) from WGS84. CH1903+ is an improved version of the original CH1903 datum, providing higher accuracy for surveying and mapping.
- Swiss National Standard: CH1903+ is the official geodetic datum for Switzerland, used for all federal surveying, mapping, and land information systems.
- Bessel 1841 Ellipsoid: CH1903+ uses the Bessel 1841 ellipsoid (a=6377397.155m, 1/f=299.1528128), a classical ellipsoid widely adopted in Central Europe.
RGF93 (Reseau Geodesique Francais 1993) is the official geodetic datum for metropolitan France, aligned with ETRS89 and equivalent to WGS84. It uses the GRS80 ellipsoid and is the basis for the Lambert-93 projection system.
- French National Standard: RGF93 is the official geodetic datum for France, used for all government mapping and GIS data.
- ETRS89 Alignment: RGF93 is aligned with ETRS89, making it compatible with European-wide spatial data infrastructure.
Lambert-93 (RGF93 / Lambert-93, EPSG:2154) is the official projected coordinate system for metropolitan France. It uses a Lambert Conformal Conic projection with two standard parallels (44°N and 49°N) to minimize distortion across the French territory. It is based on the RGF93 geodetic datum with the GRS80 ellipsoid.
- French Official Projection: Lambert-93 is the mandatory projection for all French government spatial data, replacing older local projection systems.
- Lambert Conformal Conic: Lambert-93 uses a Lambert Conformal Conic projection with standard parallels at 44°N and 49°N, providing high accuracy across metropolitan France.
Asian Systems
National coordinate systems for Asian countries including Japan, Philippines, Malaysia, Thailand, and South Korea.
JGD2011 is Japan's national geodetic system, updated after the 2011 Great East Japan Earthquake to account for significant crustal deformation.
- Post-earthquake Adjustment: JGD2011 incorporates the crustal deformation from the 2011 Tohoku earthquake.
- GRS80 Ellipsoid: JGD2011 uses the GRS80 ellipsoid, maintaining compatibility with global systems.
- Yearly Updates: JGD2011 coordinates are adjusted annually to account for ongoing crustal movement.
JGD2000 was Japan's national geodetic system before the 2011 earthquake, based on ITRF94 and the GRS80 ellipsoid.
- Tokyo Datum Replacement: JGD2000 replaced the older Tokyo Datum, which had offsets of up to 450 meters from GPS coordinates.
- ITRF94 Basis: JGD2000 is based on the International Terrestrial Reference Frame 1994 (ITRF94).
PRS92 (Philippine Reference System 1992) is the national geodetic coordinate system of the Philippines.
- WGS84-based: PRS92 uses the WGS84 ellipsoid, resulting in minimal coordinate differences from GPS-derived positions.
- 7-Parameter Required: Converting between PRS92 and WGS84 requires Helmert 7-parameter transformation for precise results.
GDM2000 is Malaysia's national geodetic reference system, based on ITRF2000 and the GRS80 ellipsoid.
- ITRF2000 Alignment: GDM2000 is based on ITRF2000, ensuring compatibility with global navigation satellite systems.
- Crustal Motion: GDM2000 accounts for regional crustal movements in Southeast Asia.
Indian 1975 is a geodetic datum primarily used in Thailand and Southeast Asian countries.
- Southeast Asian Regional Datum: Indian 1975 was designed specifically for Southeast Asia.
- 7-Parameter Required: Accurate conversion requires precise 7-parameter Helmert transformation.
KGD2002 (Korean Geodetic Datum 2002) is the official geodetic datum for South Korea, aligned with ITRF2000 at epoch 2002.0. It uses the GRS80 ellipsoid and is functionally equivalent to WGS84 for most applications.
- Korean National Standard: KGD2002 is the official geodetic datum for South Korea, used for all national mapping, cadastral surveys, and GIS data.
- ITRF2000 Alignment: KGD2002 is aligned with ITRF2000 at epoch 2002.0, providing compatibility with modern GPS/GNSS positioning and global geospatial applications.
Australian Systems
Geodetic datums for Australia, New Zealand, and the surrounding region used in government mapping and land information systems.
GDA2020 (Geocentric Datum of Australia 2020) is the current official geodetic datum for Australia, aligned with ITRF2014 at epoch 2020.0. It uses the GRS80 ellipsoid and provides sub-meter accuracy across the Australian continent.
- Current Australian Standard: GDA2020 is the official geodetic datum for Australia, replacing GDA94 and aligning with modern GNSS measurements.
- Tectonic Plate Alignment: GDA2020 accounts for the ~1.5m shift caused by the north-eastward movement of the Australian tectonic plate since 1994.
- ITRF2014 Alignment: GDA2020 is aligned with the International Terrestrial Reference Frame 2014 at epoch 2020.0, ensuring compatibility with modern GPS/GNSS positioning.
GDA94 (Geocentric Datum of Australia 1994) is the previous official geodetic datum for Australia, aligned with ITRF92 at epoch 1994.0. It uses the GRS80 ellipsoid and is functionally equivalent to WGS84 for most applications.
- Australian Geocentric Datum: GDA94 was Australia's first geocentric datum, establishing a modern reference system aligned with GPS technology.
- GRS80 Ellipsoid: GDA94 uses the GRS80 ellipsoid (a=6378137m, 1/f=298.257222101), the same as WGS84 and most modern satellite positioning systems.
NZGD2000 (New Zealand Geodetic Datum 2000) is the official geodetic datum for New Zealand, aligned with ITRF96 at epoch 2000.0. It uses the GRS80 ellipsoid and is functionally equivalent to WGS84 for most applications.
- New Zealand Standard: NZGD2000 is the official geodetic datum for New Zealand, used for all official mapping, cadastral surveys, and GIS data.
- ITRF96 Alignment: NZGD2000 is aligned with ITRF96 at epoch 2000.0, ensuring compatibility with GPS/GNSS positioning systems and modern geospatial technology.
Historical Systems
Historic coordinate systems and ellipsoids used in colonial-era mapping and legacy data preservation.
Clarke 1880 is a historic geodetic ellipsoid defined by Alexander Ross Clarke in 1880.
- Colonial Era Standard: Clarke 1880 was one of the most widely used ellipsoids during the colonial period.
- Regional Variations: Multiple regional variants of Clarke 1880 exist, each optimized for specific geographic areas.
South American Systems
Unified geodetic reference system for South America used across the continent for government mapping and GIS.
SAD69 (South American Datum 1969) is a historic geodetic reference system used across South America before the adoption of SIRGAS2000. It uses the South American 1969 ellipsoid (a=6378160m, 1/f=298.25) and requires 7-parameter Helmert transformation for accurate conversion to WGS84. SAD69 remains important for working with legacy mapping, cadastral records, and infrastructure data throughout the continent.
- South American Standard: SAD69 was the first continent-wide unified geodetic datum for South America, providing a consistent reference framework across national boundaries for mapping and surveying.
- 7-Parameter Required: SAD69 to WGS84 conversion requires a 7-parameter Helmert transformation. Common approximate parameters are dx=-57, dy=1, dz=-41 (meters, zero rotations/scale), but regional variations exist across different countries.
- Legacy Data Preservation: Vast archives of topographic maps, cadastral records, and engineering surveys across South America use SAD69 coordinates. Converting this legacy data is critical for modern GIS applications.
Corrego Alegre is a historic Brazilian geodetic datum used primarily before the adoption of SIRGAS2000. It uses the International 1924 (Hayford) ellipsoid (a=6378388m, 1/f=297) and requires 7-parameter Helmert transformation for accurate conversion to WGS84. Corrego Alegre remains important for working with legacy Brazilian mapping, cadastral records, and infrastructure data.
- Brazilian National Datum: Corrego Alegre served as the official geodetic datum for Brazil for over three decades, forming the basis for the country's national mapping and land surveying infrastructure.
- 7-Parameter Required: Corrego Alegre to WGS84 conversion requires a 7-parameter Helmert transformation. Common approximate parameters are dx=-206, dy=172, dz=-6 (meters), but regional variations exist across different areas of Brazil.
- Hayford Ellipsoid: Corrego Alegre uses the International 1924 (Hayford) ellipsoid (a=6378388m, 1/f=297), the same ellipsoid used by the European Datum 1950 (ED50).
SIRGAS2000 (Sistema de Referencia Geocéntrico para las Américas 2000) is the official geodetic datum for South America, aligned with ITRF2000 at epoch 2000.0. It uses the GRS80 ellipsoid and is functionally equivalent to WGS84 for most applications. It is the mandatory system in Brazil and widely adopted across the continent.
- South American Standard: SIRGAS2000 is the official geodetic datum for South America, used across the continent for government mapping and GIS.
- ITRF2000 Alignment: SIRGAS2000 is aligned with ITRF2000 at epoch 2000.0, ensuring compatibility with modern GPS/GNSS positioning.
African Systems
National and regional geodetic datums for African countries used in official surveying, mapping, and geospatial data infrastructure across the continent.
Hartebeesthoek94 is the official geodetic datum for South Africa, aligned with WGS84 and using the WGS84 ellipsoid (a=6378137m, 1/f=298.257223563). It is functionally equivalent to WGS84 for most practical applications, making conversion between the two systems essentially transparent. Hartebeesthoek94 is maintained by the Chief Directorate: National Geospatial Information (CD:NGI) of South Africa.
- South African Standard: Hartebeesthoek94 is the official geodetic datum for South Africa, used for all government surveying, mapping, and spatial data since 1994.
- WGS84 Compatibility: Hartebeesthoek94 uses the same WGS84 ellipsoid (a=6378137m) and is functionally equivalent to WGS84, making conversion transparent for most GIS applications.
Arc 1950 is a historic geodetic datum used in East Africa, covering countries including Kenya, Tanzania, Uganda, Ethiopia, Somalia, and Sudan. It uses the Clarke 1880 ellipsoid (a=6378249.145m, 1/f=293.465) and requires 7-parameter Helmert transformation for accurate conversion to WGS84. Arc 1950 was part of a series of African datums established during the post-war mapping campaigns.
- East African Standard: Arc 1950 served as the primary geodetic datum for East African countries, providing a consistent reference framework for mapping and surveying across national boundaries.
- 7-Parameter Required: Arc 1950 to WGS84 conversion requires a 7-parameter Helmert transformation. Parameters vary by country and region within East Africa. Consult local surveying authorities for official values.
Arc 1960 is a historic geodetic datum used in East and Central Africa, covering countries including Kenya, Tanzania, Uganda, Burundi, and Rwanda. It uses the Clarke 1880 ellipsoid (a=6378249.145m, 1/f=293.465) and requires 7-parameter Helmert transformation for accurate conversion to WGS84. Arc 1960 was established as a refinement of the earlier Arc 1950 system.
- East & Central African Standard: Arc 1960 served as a refined geodetic datum for East and Central Africa, improving upon Arc 1950 with additional survey observations for better accuracy.
- 7-Parameter Required: Arc 1960 to WGS84 conversion requires a 7-parameter Helmert transformation. Parameters vary by country and region. Consult local surveying authorities for official values.
Format Conversions
Common coordinate format representations including Degrees/Minutes/Seconds, Decimal Degrees, Degrees and Decimal Minutes, and the Military Grid Reference System.
DMS (Degrees, Minutes, Seconds) is a sexagesimal coordinate format where angles are expressed in degrees (°), minutes ('), and seconds ("). It is the traditional format for paper maps and GPS devices.
- Traditional Format: The sexagesimal (base-60) notation has been used for centuries in navigation and cartography, remaining the standard for paper maps and marine charts.
- Human Readable: DMS coordinates provide intuitive degree, minute, and second breakdowns that are easy to read and manually plot on paper maps with grid overlays.
- GPS Compatible: Many GPS receivers and navigation devices can display coordinates in DMS format, making it a widely supported standard across different equipment brands.
DDM (Degrees and Decimal Minutes) is a coordinate format combining whole degrees with minutes expressed as a decimal fraction, widely used in GPS receivers and marine navigation.
- GPS Standard: DDM is the native output format for most GPS receivers and the standard format used in NMEA 0183 sentences transmitted by marine and aviation GPS devices.
- Precision Balance: DDM offers better precision than DMS for the same number of digits, providing sub-meter accuracy with just 3-4 decimal places in the minutes field.
- Chart Compatible: DDM is the preferred format for plotting positions on paper charts and maps, as the decimal minutes align naturally with chart grid markings.
Decimal Degrees (DD) is a coordinate format where latitude and longitude are expressed as decimal fractions of degrees, the most widely used format in digital mapping and GIS software.
- Digital Standard: Decimal degrees is the native format for virtually all digital mapping platforms, GIS software, and geospatial databases worldwide.
- Direct Calculation: Coordinates in decimal degrees can be used directly in distance, bearing, and area calculations without requiring DMS-to-decimal conversion.
- Compact Storage: Decimal degrees require fewer characters to represent the same precision as DMS, making it more efficient for data storage and API transmission.
BNG (British National Grid) is the official projected coordinate system for the United Kingdom, based on the OSGB36 geodetic datum and the Transverse Mercator projection optimized for the British Isles.
- UK National Grid: BNG provides a unified metric grid system covering all of Great Britain with easting and northing coordinates in meters, eliminating the need for UTM zone calculations.
- Transverse Mercator Projection: BNG uses a customized Transverse Mercator projection centered at 2°W with a scale factor of 0.999601272, optimized to minimize distortion across the UK landmass.
- Metric Coordinates: BNG coordinates are expressed in meters (easting and northing), with a false origin at 400,000m easting and -100,000m northing southwest of the Isles of Scilly.