mapverter

EPSG:3003 Coordinate Converter

Convert Gauss-Boaga west zone coordinates from Italian GIS files. Check EPSG:3003, datum-shift limits and output CRS before exporting SHP or CSV.

Monte Mario / Italy zone 1

Area of use (longitude / latitude): west 5.93°, south 36.53°, east 12°, north 47.04°.

PROJ definition

+proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl +units=m +no_defs +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
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SHP (zip, or .shp with .shx, .dbf, .prj), KML, KMZ, GeoJSON, GPX, CSV

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Gauss-Boaga west zone

EPSG:3003 is Monte Mario / Italy zone 1, commonly called Gauss-Boaga fuso Ovest, a Transverse Mercator projection in metres on the International 1924 ellipsoid of the Monte Mario datum. Its central meridian is 9° E, the latitude of origin is 0°, the scale factor is 0.9996, the false easting is 1,500,000 m and the false northing is 0 m.

The definition bundled with mapverter gives an area of use from 5.93° to 12° E and 36.53° to 47.04° N. As a reference, the point at 9.19° E, 45.46° N is about x = 1,514,883 m and y = 5,034,090 m.

West zone and east zone

The eastern zone is EPSG:3004, Monte Mario / Italy zone 2, with a central meridian of 15° E and a false easting of 2,520,000 m. Neither zone uses the same datum as ETRS89 or RDN2008, even where the projection looks similar.

How mapverter handles EPSG:3003

  • A .prj is matched by its EPSG code or by its projection parameters, so ESRI-style names such as Monte_Mario_Italy_1 are recognized as well.
  • Without a .prj, the Italian interface offers EPSG:3003 first among the candidates that fit the data. The English interface does not suggest it, so search for 3003 by EPSG code in the coordinate system picker and check the result on the map.
  • mapverter converts with the bundled seven-parameter datum shift, Monte Mario to WGS 84 (4), whose published accuracy is 4 m. In a check at three test points it matched PROJ's default transformation on the mainland but differed by about 6.3 m in Sardinia, where PROJ prefers a separate regional transformation. This is a sample result, not a maximum error guarantee.
  • This page presets EPSG:3003 as the target for SHP and CSV output. KML, KMZ, GeoJSON and GPX always use WGS 84.

Frequently asked questions

Is EPSG:3003 the western Gauss-Boaga zone?
Yes. EPSG:3003 is the western zone, fuso Ovest. The eastern zone uses EPSG:3004 and different projection parameters.
How accurate is the datum conversion?
mapverter uses one fixed datum transformation with a published accuracy of 4 m. It does not select a local correction for every location, so metre-level differences can remain, especially in Sardinia and Sicily, where PROJ prefers regional transformations.
Is it suitable for precise cadastral transformations?
Use the transformation and control points specified by the data provider for work requiring surveying accuracy. The browser conversion does not promise that accuracy.
Can I keep EPSG:3003 in KML?
No. KML uses WGS 84 longitude and latitude. Choose SHP or CSV to keep EPSG:3003 coordinates.