What do the colours of the United States flag mean?

Red: hardiness and valour. White: purity and innocence. Blue: vigilance, perseverance and justice.

How do you tell the United States flag from the Liberia one?

Liberia has eleven stripes and a single large white star on a blue canton that covers only the top five stripes. The ratio, 10:19, is identical, which is not coincidence.

When was the United States flag adopted?

The current design dates from 1960, and its official ratio is 10:19.

The flag of United States

Thirteen horizontal stripes alternating red and white, starting and ending with red, and a blue canton in the top hoist corner holding fifty white five-pointed stars in nine offset rows.

Ratio 10:19 · current design adopted 1960

United States

Field and colours only. Not shown: thirteen red and white stripes with a blue canton of fifty stars.

The 10:19 ratio is unusually long and comes from Executive Order 10834 of 1959, which also fixed the exact star layout; flags sold at 3:5 or 2:3 are technically non-conforming and extremely common. The colour meanings are not in the flag law at all — they were given by Charles Thomson in 1782 for the Great Seal, and were attached to the flag afterwards. The fifty-star arrangement was designed in 1958 by Robert G. Heft, a seventeen-year-old Ohio student, as a school project that initially earned a B−. There is no provision for removing a star, only for adding one.

Flags it gets confused with

Flag	How to tell them apart
Liberia	Liberia has eleven stripes and a single large white star on a blue canton that covers only the top five stripes. The ratio, 10:19, is identical, which is not coincidence.
Malaysia	Malaysia has fourteen stripes and a yellow crescent and fourteen-pointed star on the blue canton, not stars.

What the colours mean

Flag laws usually specify a Pantone chip, a CMYK mix or just a colour name. Converting any of those to sRGB is lossy, which is why published hex values disagree.

The symbols on it

What	What it stands for
Thirteen stripes	The thirteen colonies that declared independence in 1776
Fifty stars	One for each state; a star is added on the 4 July after admission

Ratio: 10:19
Current design adopted: 1960
Colours: red, white, blue

The specification names Pantone 193 C and 281 C, not hex. #B31942 and #0A3161 come from the official CMYK conversion; #B22234 and #3C3B6E, from an older RGB approximation, are equally widespread online.

Common questions

What does the flag of United States look like?: Thirteen horizontal stripes alternating red and white, starting and ending with red, and a blue canton in the top hoist corner holding fifty white five-pointed stars in nine offset rows.
What do the colours of the United States flag mean?: Red: hardiness and valour. White: purity and innocence. Blue: vigilance, perseverance and justice.
How do you tell the United States flag from the Liberia one?: Liberia has eleven stripes and a single large white star on a blue canton that covers only the top five stripes. The ratio, 10:19, is identical, which is not coincidence.
When was the United States flag adopted?: The current design dates from 1960, and its official ratio is 10:19.

United States Capital, area, population and currency
The flag of Malaysia Routinely mistaken for this one
Every flag with red in it
The flag of United Kingdom Ratio 1:2
The flag of Canada Ratio 1:2
The flag of France Ratio 2:3
The flag of China Ratio 2:3
The flag of Germany Ratio 3:5
The flag of Russia Ratio 2:3
The flag of Italy Ratio 2:3
The flag of Mexico Ratio 4:7

Sources

Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked