Flags with blue and yellow
43 of the 196 national flags here contain blue and yellow; 4 use only those colours.
Only blue and yellow (4)
With blue and yellow and other colours too (39)
What the list shows
43 of the 196 national flags here contain blue and yellow; 4 use only those colours. That is 22% of the flags in this list. The list is the 196 states the United Nations recognises as members or observers, plus Kosovo; territories are left out because most of them share their parent's flag.
By continent: Africa 16 of 54, Europe 9 of 46, North America 6 of 22, South America 5 of 13, Asia 4 of 47, Oceania 3 of 14. Africa has the most (16), and South America has the highest share (38% of its flags).
Colours and layout
Other colours that turn up alongside them: red on 26, white on 19, green on 18, black on 8. For comparison, red is on 77% of all 196 flags and white on 69%.
Layout: 12 of these 43 are built from stripes (8 horizontal, 4 vertical) and 31 are not. Across all 196 flags the stripe share is 42%.
Exactly these colours
Exactly these colours and no others: 4 — Kazakhstan, Palau, Sweden, Ukraine. The other 39 add at least one more colour, often in a small emblem or a canton.
Capitals of the first few, to place them: Andorra (Andorra la Vella), Antigua and Barbuda (St. John's), Bahamas (Nassau), Barbados (Bridgetown), Bosnia and Herzegovina (Sarajevo), and so on down the list. The shortest names here are Chad, Gabon and Palau.
How the labels were made: colours are measured from the flag image (a colour counts if it covers at least 0.6% of the flag, edges excluded, so a small emblem can add a colour), and symbols were labelled by hand. A flag with a detailed coat of arms can legitimately appear under several symbols. If a flag looks mislabelled, the corrections link on the about page is the way to say so.
How the flags are labelled. Images are from the open-source flag-icons set (MIT). Colours are measured from each image; symbols are labelled by hand. Names follow the source lists and do not imply any judgment on the status of any territory. Sources and limits.