The colours of the flag are calculated from the official Dutch government standards document which describes textile colours called Normblad NEN 3055:
De kleur rood moet zijn helder vermiljoen met de trichromatische coördinaten X=17,2; Y=9,0 en Z=2,6.
De kleur blauw moet zijn kobaltblauw met de trichromatische coördinaten X=7,8; Y=6,8 en Z=26,7.
These colour values are defined in the CIE's chromaticity diagram. To convert these values to RGB, a daylight value of D65 was used. The resulting colours are: #AE1C28 (red), and #21468B (blue).