Hex Colors and RGB Conversion Explained

How hexadecimal colors map to channels

Hexadecimal is base 16: its digits are 0–9 and A–F. In CSS opaque #RRGGBB notation, the first pair represents red, the second green, and the third blue. Each pair ranges from 00 (0) to FF (255). Letter case does not change the value.

For #F59E0B, red is F5 = 15 × 16 + 5 = 245; green is 9E = 9 × 16 + 14 = 158; blue is 0B = 0 × 16 + 11 = 11. The result is rgb(245, 158, 11). Calzivo also shows rgba(245, 158, 11, 1), whose alpha value 1 means fully opaque, and normalized #F59E0B.

Three-digit shorthand

CSS shorthand #RGB duplicates each hexadecimal digit: #abc expands to #AABBCC. Thus AA = 170, BB = 187, and CC = 204. It does not append zeroes or interpret the three digits as decimal numbers.

CSS syntax and Calzivo input convenience

CSS hexadecimal color notation includes the leading #. The Hex to RGB Converter additionally permits those same three or six ASCII hex digits without # as an input convenience; that bare form is not itself CSS hex-color syntax. Calzivo accepts at most one leading # and does not trim whitespace. Output is normalized to uppercase hexadecimal.

Opaque-only scope

CSS Color Level 4 also defines hex forms with alpha, but this tool intentionally accepts only three or six digits. It rejects four- and eight-digit alpha notation, invalid lengths, prefixes such as 0x, and non-hex characters. It does not convert to HSL, HSV, or CMYK and does not assess contrast, accessibility, or palette suitability.