Formula
HEX = RGB channels 0–255 written as two hex digits eachK = 1 − max(R′,G′,B′); C = (1 − R′ − K) ÷ (1 − K) How it works
Screens mix red, green and blue light, so every web color is ultimately three numbers from 0 to 255. HEX is just those three numbers in hexadecimal (#3B82F6 = 59, 130, 246). HSL and HSV describe the same color in a more human way: a hue angle around the color wheel, plus saturation and lightness (or value/brightness). Designers use HSL to make a color lighter or darker without shifting its hue.
Paste a color in whatever form you have — #rgb, #rrggbb or #rrggbbaa hex, modern space-separated rgb(59 130 246 / 50%), hsl(), hsv() or hsb(), cmyk() or a common CSS color name — and every other format appears. Alpha transparency is carried through to 8-digit hex and rgba().
CMYK here is the simple mathematical conversion. Real printing depends on the paper, ink and ICC color profile, so ask your printer for a proof when exact color matters. The readable text suggestion compares WCAG contrast ratios for white and black text; 4.5:1 or more passes for body text.
Frequently asked questions
Why does converting back and forth change a value by one?
RGB channels are whole numbers, while HSL and CMYK percentages are rounded for display. Converting a rounded value back can land one step away. The underlying color is visually identical.
What is the difference between HSL and HSV?
Both use the same hue. In HSL, 100% lightness is always white and 50% is the pure color. In HSV (also called HSB), 100% value is the pure color at full brightness, and white needs 0% saturation. Photoshop's color picker uses HSB; CSS uses HSL.