I was doing some riddles with my daughter today and mentioned some nations. She had to 'calculate' how many of those nations' flags had the color red in them.

As it happened, all of them did. In addition, a lot of them contain white (which I guess makes sense since the color of cloth is white) and blue.

However, red seems to be the color that is most used and in this Wikipedia article it seems to be confirmed.

UPDATE: This article on Wikipedia shows that 30% of the surface on all flags is red, with white being a distant second with 18%.

  • Is this really surprising? There's only so many basic colours to choose from. Also one reason white is popular is because it contrasts well with the darker colours. Seems more of a general design issue than a history question unless you want to ask about a specific flag's origins.
    – Semaphore
    Apr 17 '15 at 7:49
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    @Lohoris But it isn't really "vastly predominant". There are six major colours, and an average each flag uses three. That's a baseline 50% chance to be on a flag right there. While red is certainly more popular than the others, very many flags also contains blue, white, etc. Also I wouldn't blame it on the Communists - red (gules) has always been popular in heraldry too. It just seems like a popular colour for a vibrant / catchy design.
    – Semaphore
    Apr 17 '15 at 11:26
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    @T.E.D. This article on Wikipedia: en.wikipedia.org/wiki/National_flag#Colours says that Red covers 30% of the surface of all flags. White is a distant second with 18%... Apr 17 '15 at 20:57
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    There's some color analysis here too: blog.wolfram.com/2009/02/12/flag-analysis-with-mathematica (the color-by-area conclusion is the same but there's some more detail)
    – Cascabel
    Apr 17 '15 at 22:12
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    @user1914292 If you count dark and light blue together, then blue is second, but still, only 20%.
    – Cascabel
    Apr 20 '15 at 18:23

The colors come from the heraldic tradition, especially European and former European colonies' flags and coats of arms. In this summary on heraldry the basic heraldic colors are:

  • Yellow (Gold)
  • White (Silver)
  • Red
  • Blue
  • Green
  • Purple
  • Black

If you check existing flags, you will find that they are almost all made in these colors. According to the link provided by Lohoris, the sum of the area of heraldic colors on flags is more than 99.6% of the area on flags worldwide. Many flags come from the medieval era, when heraldry was taken seriously. Later (even nowadays) these same colors have served as a guideline to make flags. Red is not really overrepresented in flags (red area: 30.3%, second is blue 21.15%). A weak preference comes from "Color psychology". There are studies on color's effect on the human mind. It is an another topic in Psychology, worth mentioning, but this part is not really just History. Red can represent many abstract thoughts from love, blood, courage and many others.

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    Found it! No time to read it carefully now, but it confirms red wins (148), with the caveat that white is close by (140) and the others are quite behind (102, 89, …). I thought white was not so close, but otherwise it confirms what I thought.
    – o0'.
    Apr 17 '15 at 10:18
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    Thanks for the research! Red really wins, but not really overwhelmingly, could approve the psychology behind it. Apr 17 '15 at 10:39
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    @Semaphore in my observation I also noticed that white occurs a lot, but I was thinking that would be the case since the cloth is already white to begin with. Furthermore there's always debate whether white is really a color in the true sense. For me at least it's not on the same level as blue, yellow etc. If you take that into account than red occurs 50% more than the next best one. Apr 17 '15 at 11:50
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    @user1914292 Cloth is not actually necessarily white, nor would that have been a factor for flag design in general. And white is obviously a colour in this (or any non-inane) context. I mean, its your freedom to ignore its inconvenient popularity, but that doesn't really improve the premise.
    – Semaphore
    Apr 17 '15 at 12:03
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    @user1914292 take a note that red is an intensive color, it is very visible, and in the nature it means "I want to be something what can be seen", and this basic meaning didn't change with human race. Green, white, blue (other major colors) are common in nature (leaves, clouds, water, sky). Apr 17 '15 at 12:25

As was pointed out by others, colours in national flags are derived from older coat of arms or other symbols derived from medieval heraldry. That one itself become more or less formalized in the early 13th century, from a habit taken (especially during the Crusades) to hoist highly distinguishable colour patterns so as to promote warrior recognition on a dusty battlefield. Thus a relatively small set of primary colours, including red, which is very visible in a countryside landscape (the human eye is most sensitive to green, not red, but Nature is full of green so a green flag does not stand out the way a red flag does).

Among heraldry "rules" is the one about tinctures that says that you should put only a metal on a colour, or vice-versa, but not metal on metal or colour on colour. "Metal" is or (yellow) or argent (white); other tinctures are "colours". This rule is one of maximum visibility: to make details visible, they must be painted with tinctures that don't blend. These rules can still be seen in action on car license plates; for instance, old French plates were white-on-black, while recent ones are black-on-white or black-on-yellow; Belgian licence plates are red-on-white; and so on. A consequence is that most coat of arms contained some white or yellow (hard to avoid, with the rule explained above), which now shows on national flags.

It is noteworthy that flag evolution has not been straight from medieval banners to national flags; maritime flags played an important part, and visibility (in a nautical context) was the whole point of such flags.

While the above talks about plausible reasons why red would be most favoured (mainly because it is highly visible), this may be all purely coincidental. Worldwide statistics on national flags, by definition, work over nations, and a lot of nations were created in recent history. In particular, most of Africa (now 54 UN members) became independent countries in the last 70 years, and "invented" their flags at that time. Most of them reused some or all of the colours from the Pan-African flag, including the red. Warfare technology being what it is now, flag visibility can be said to no longer have any practical consequence; symbolism is a much stronger force in national flag colour selection. These African flags alone account for more than a quarter of current national flags, so such coincidental effects cannot be dismissed easily.

A similar effect may be observed in formerly communist states, who tended to use the "communist red" in their flags (e.g. China, Vietnam).

Yet another case is the Red Ensign that "pollinated" a lot of ulterior national flags thanks to the ubiquitousness of the British Empire in the late 1800s. For instance, Canada's flag red part is a deliberate reference to England (while the white part is explicitly a reference to the French pre-Revolution inheritance).

  • The Red Ensign would also have been influenced in its colour by the Cross of Saint George in its canton. That in turn shares a heritage with many red flags like those of Switzerland and Denmark, and the older Holy Roman Empire war-flag. Hence that "pollination" you talk of is a later phase of one that brings in yet further countries (and many cities and other regions).
    – Jon Hanna
    Apr 20 '15 at 13:22

Flags were used as a standard in battle. Red is an arresting colour for mammals and birds, which is why most ripe fruit is red. You can imagine that red is likely to be more visible and less likely to blend in than blue or white (sky) grey or black (smoke) or green or brown (trees, landscape etc.)

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    I agree that there are some biological reasons. Humans (and possibly other animals) perceive red as something special. For example, in Russian, the word for "red" is almost the same as the word for "beautiful", and it is clear that in the past this was the same word.
    – Alex
    Apr 17 '15 at 12:04
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    The second point is dubious. The blue woad dye was actually pretty common and very cheap in Medieval Europe; a pale blue (requiring less dye) would have been one of, if not the cheapest, of coloured clothes.
    – Semaphore
    Apr 17 '15 at 12:16
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    Actually purple dye was the most expensive in roman and medieval times. Apr 17 '15 at 12:26
  • If the 'used as a standard in battle' was a key reason, we would expect use of red to decrease in flags of countries formed after the Middle Ages (unless they were derivatives of older flags).
    – smci
    Apr 18 '15 at 3:43
  • Standards were used in battle up until the early 20th century. Many of today's countries existed by then, and even the ones which didn't exist yet already had a flag (because there were groups that wanted to bring them into existence). Red's utility as an arresting colour isn't limited to battle standards: flags are designed to be eye-catching, which red is, and brown (for example) isn't. They have a point about woad... removed.
    – Ne Mo
    Apr 18 '15 at 10:31

Probably a lot of flags contain red because red represents courage, revolution, hardiness, blood, and/or valor.

Red color also depicts sacrifice the hardships faced for a nation to be made. I believe there is a scientific reason too for having red among the colors in national flag. That is red being the color with the greatest wavelength in our visible spectrum red can be viewed from great distance and in case of the national flag which identifies a nation the color red makes sure that the flag is noticed.

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    not a bad point (at least I am certain it shouldn't deserve -1 ), please extend your answer Apr 17 '15 at 12:20
  • I can't find anything at that link that has anything to do with your answer, so I'm editing it out. If you have a deeper link on that website you were thinking about, feel free to edit your answer and put that in.
    – T.E.D.
    Apr 17 '15 at 19:08

Red dyes were some of the earliest developed, and thus more likely to be used for banners and flags. see http://www.straw.com/sig/dyehist.html


A very non historical answer. For what it's worth. I'm answering the question "why do people like or notice red colour more?" and extrapolate to flags. Many of the assertions below are well recognised in evolutionary biology but I did not look for sources for each of them.

Most land plants are green because they use chloroplasts to power the synthesis of organic molecules from carbon dioxide (Calvin cycle). For land plants the applicable lineage of chloroplasts are green (red for some sea weeds chloroplasts).

Red is the complementary colour to green (as all artists well know). Which means that red and green offer the strongest contrast. Another pair of complementary colours is blue and yellow (=> Swedish flag anyone? :).

There is therefore an evolutionary pressure for plants to advertise ripen fruit as red and conversely hide immature fruit as still green. Fruit consumers (who pay for their consumption by disseminating the seeds) have synchronously progressively experienced the complementary evolutionary pressure to see from far away and to be attracted by red objects. For instance the animal species most receptive to red are African primates - while most other animal species don't see red at all. Notable exceptions are birds (heavy fruit and berry consumers) and crustaceans (not sure why because red is rare in the sea). Similarly aphids are attracted by light green (young poison free leaves) and pollinator insects by ultraviolet (to spot flowers).

So young primates like colours (ever noticed marketing techniques to have your kid grab their yoghurt pack in the shops?) because in their original rain forest habitat it's a competitive advantage to be attracted by vitamin and nutrient loaded fruit. We, as human adults (with interestingly enough regional differences) are still very fond of red.

It remains to be seen of course whether bees national flags predominantly contain ultraviolet motifs and aphids flags green ones. :)

Overall flags, designed as group emblems, must express pride and possibly inspire awe (red is also used to advertise power in some primates - Gelada baboons chest for instance).

About regional differences - this is my own interpretation here. Northern hemisphere (colder countries) flag have also a lot of blue because nice weather (blue sky) allows to synthesize more vitamin D and it's a competitive advantage for its inhabitants (originally coming from the African plains) to have blue eyes, light skin (with less melanin) and to research exposure to sun light.

Conversely African flags were light is plentiful have very little blue but are very colourful.

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