The RD (Rijks-Driehoek) system is the coordinate system used by the Dutch geographical service. Conversion to and from WGS84 (World Geodetic System; latitude and longitude pairs) is not entirely straightforward. The conversion software is based on the formulas and coefficients in this (Dutch) document (contains a summary in English). This service works for coordinates within the Netherlands (and some area outside it). Highest precision is achieved West of 6.0°E. You can enter either RD-coordinates (in meters) or WGS84-coordinates in degrees using a decimal point. The coordinates can be entered in any order.