Converting RD coordinates to WGS84

RD New (Rijksdriehoekstelsel, the Dutch national grid) is the Dutch coordinate system for surveying and maps, registered as EPSG:28992 (Amersfoort / RD New). It is a stereographic projection on the Amersfoort datum with the Bessel 1841 ellipsoid. The coordinates are x and y in metres. EPSG gives the area of use as the Netherlands onshore, including the Wadden Sea and the 12-mile zone. The false origin lies at x = 155,000 and y = 463,000 metres.

WGS84 (EPSG:4326) is the worldwide system of GPS. Positions are latitude and longitude in degrees. Web maps, mobile devices and GeoJSON use this system by default. The order (longitude, latitude) in GeoJSON versus the order (latitude, longitude) in many other APIs is a well-known source of errors.

Almost all Dutch government geodata, such as the datasets on Dutch open data, is stored in RD New, so anyone combining it with web maps ends up needing this conversion.

The answer depends on the method. The official transformation is called RDNAPTRANS™ and is maintained by the NSGI; the current version is RDNAPTRANS™2018. The parameters and formulas are freely available, though the download requires a request form. The Dutch guideline on coordinate reference systems (Geonovum) states:

Voor de uitwisseling van geo-informatie binnen Europa is het nadrukkelijke advies om altijd de weg via ETRS89 te kiezen. Bij gebruik van de actuele RDNAPTRANS™ procedure is daarbij voor het Nederlandse deel een nauwkeurigheid op centimeterniveau gewaarborgd.

Source: Geonovum, Handreiking gebruik coördinaatreferentiesystemen. In English: for exchanging geo-information within Europe, always go through ETRS89; with the current RDNAPTRANS™ procedure, centimetre-level accuracy is guaranteed for the Dutch part.

The own test compared a widely used polynomial approximation with the RD and WGS84 coordinates that the PDOK Locatieserver supplies for six addresses, from Vaals to Groningen. The deviation was each time between 0.295 and 0.302 metres, an almost constant shift. It is a measurement against the PDOK values, not a check against RDNAPTRANS itself. More about that service is on the page about the PDOK Locatieserver.

The difference between WGS 84 and ETRS89 (the European reference system) in the Netherlands is about 88 centimetres on 1 January 2025 and grows by about 2.4 centimetres per year. For most web applications that does not matter. For land surveying it does.

The false origin of the RD system, x = 155,000 and y = 463,000, lies about 850 metres from this point. If you want to show your own RD points in a map viewer, combine the conversion with a map solution or, for municipalities, a GIS viewer. If the points come from PDOK, request both systems directly instead of converting.

The converter above runs in your browser. The coordinates you enter are not sent to a server and are not stored. The tool uses an approximation formula, so treat its output as accurate to roughly a metre, in line with the table above, and not as a survey result. Heights are not converted: RD New with NAP heights needs the full RDNAPTRANS procedure. The tool is meant for quick checks, for example to see whether a point from a Dutch dataset lands in the right place on a web map.