The official ratio of the flag of the Netherlands is 2:3.
That ratio means the flag is two units high for every three units of length. The Dutch tricolour consists of three equal horizontal bands: bright vermilion at the top, white in the middle and cobalt blue at the bottom.
The Netherlands’ flag developed from the Prince’s Flag, which originally used orange, white and blue in the sixteenth century. Orange was gradually replaced by red, probably because red dye was more stable and more visible. The red-white-blue arrangement became firmly established over time.
The 2:3 proportions are standard, although the ratio is not formalised by Dutch law in the same way as some national flags. A frequent mix-up is Luxembourg’s flag: it also uses red, white and blue horizontal bands, but Luxembourg’s flag is generally longer and uses lighter shades. The Dutch flag’s color specifications were standardised in the twentieth century.