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    EPSG reference

    EPSG:30731 — Nord Sahara 1959 / UTM zone 31N

    Nord Sahara 1959 / UTM zone 31N (EPSG:30731) — a Projected (metres) system on the a=6378249.145 datum, used in Algeria. Parameters, proj4, WKT, accuracy ±0.1 m, plus a f…

    At a glance

    EPSG
    30731
    Name
    Nord Sahara 1959 / UTM zone 31N
    Kind
    Projected (metres)
    Family
    Universal Transverse Mercator (UTM)
    Ellipsoid
    a=6378249.145
    Accuracy
    ±0.1 m (vs PROJ)
    Countries
    Algeria
    Convert from this system now

    Area of use

    West0.00°
    South18.97°
    East6.01°
    North38.77°

    Projection parameters

    Projectionutm
    UTM zone31
    Semi-major axis6378249.145
    Inverse flattening293.465
    Unitsm
    Helmert shift to WGS84-267.407,-47.068,446.357,-0.179423,5.577661,-1.27762,1.204866
    proj4
    +proj=utm +zone=31 +a=6378249.145 +rf=293.465 +units=m +no_defs +towgs84=-267.407,-47.068,446.357,-0.179423,5.577661,-1.27762,1.204866
    WKT (ESRI)
    PROJCS["Nord Sahara 1959 / UTM zone 31N",GEOGCS["GCS_Nord Sahara 1959 / UTM zone 31N",DATUM["D_Custom_6378249.145",SPHEROID["Custom_6378249.145",6378249.145,293.465],TOWGS84[-267.407,-47.068,446.357,-0.179423,5.577661,-1.27762,1.204866]],PRIMEM["Greenwich",0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",3],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0],UNIT["Meter",1],AUTHORITY["EPSG","30731"]]

    Sample conversion

    Algeria capital: WGS84 3.05880, 36.75380 → EPSG:30731 505315.393, 4067260.060

    Values are within ±0.1 m at the test point.

    About the Universal Transverse Mercator (UTM) family

    Nord Sahara 1959 / UTM zone 31N is a Universal Transverse Mercator zone — a 6°-wide belt of the worldwide UTM system, in metres, centred on a meridian carefully chosen so distortion stays low across the zone. It is the everyday working grid for GPS-derived surveying in Algeria.

    The classic field mistake with UTM is using the wrong zone: a point one zone away is easily hundreds of kilometres off. Always confirm the zone number (and the hemisphere) before importing coordinates, and remember that UTM eastings are offset by a 500 km false easting so they never go negative.

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    FAQ

    What is EPSG:30731?
    It is the coordinate system “Nord Sahara 1959 / UTM zone 31N”, a Projected (metres) system in the Universal Transverse Mercator (UTM) family, identified worldwide by the code EPSG:30731.
    What datum does it use, and how accurate is it?
    It is based on the a=6378249.145 ellipsoid and it carries Helmert parameters to WGS84. The residual at the test point is about ±0.1 m versus PROJ; for centimetre work use a geodetic adjustment service.
    Where is this system used?
    It is used in Algeria. This page shows its area of use as a coordinate rectangle above.
    How do I convert EPSG:30731 to WGS84?
    Use the free coordinate converter above (preloaded with this system) to convert to WGS84, UTM, or any other system, within a ±0.1 m residual.

    You may also need: Arab-world coordinate converter · Surveying file format converter · Batch coordinate file converter