The national flag of Sweden (Sveriges flagga) consists of a yellow or gold Nordic cross (i.e. a horizontal cross extending to the edges, with the crossbar closer to the hoist than the fly) on a field of light blue. The Nordic cross design traditionally represents Christianity. The design and colours of the Swedish flag are believed to have been inspired by the present coat of arms of Sweden of 1442, which is blue divided quarterly by a cross pattée of gold, and modelled on the Danish flag. Blue and yellow have been used as Swedish colours at least since Magnus III's royal coat of arms of 1275.
The Swedish flag is one of only five that use the ratio 5:8, the others being Argentina, Guatemala, Palau, and Poland.
It is one of only four flags that currently use the colour scheme of blue and yellow, the others being Kazakhstan, Palau, and Ukraine.
The dimensions of the Swedish flag are 5:2:9 horizontally and 4:2:4 vertically. The dimensions of the Swedish flag with a triple-tail are 5:2:5:8 horizontally and 4:2:4 vertically. The colours of the flag are officially established through the Natural Color System to be NCS 0580-Y10R for the shade of yellow, and NCS 4055-R95B for the shade of blue. They are also specified to Pantone PMS 301 C/U for blue and PMS 116 or PMS 109 U for yellow. The square-cut Swedish state flag is identical to the civil ensign. The Swedish law does not regulate the design of the Swedish pennant, but it is recommended that its colour scheme should correspond with that of the flag.
The triple-tailed flag (tretungad flagga) is used as a naval ensign (örlogsflaggan). Its overall ratio, including the tails, is 1:2. The flag is also used as the Swedish naval jack (örlogsgösen). The jacks are smaller than the ensigns, but they have the same proportions. The Swedish swallowtail flag was originally the King's personal emblem, or the emblem representing a command conferred by the King. It was at first two-pointed, but by the mid-17th century, the distinctive swallowtail with tongue appeared.