Last updated
CMYK vs RGB: Two Different Color Models
CMYK and RGB represent color using fundamentally different physical principles. RGB (Red, Green, Blue) is an additive color model used by screens: mixing all three at full intensity produces white light. CMYK (Cyan, Magenta, Yellow, Key/Black) is a subtractive model used in printing: inks absorb (subtract) light, and mixing all three produces a muddy dark brown — which is why a separate black (K) ink is used for clean blacks and text.
This fundamental difference means that CMYK-to-RGB conversion is always an approximation. Some colors achievable in print (especially vivid cyans and magentas) fall outside the RGB gamut, and vice versa. Professional print workflows use ICC color profiles to manage this conversion accurately.
The Conversion Formula
The mathematical conversion from CMYK (values 0–100%) to RGB (values 0–255) is:
R = 255 × (1 - C/100) × (1 - K/100)
G = 255 × (1 - M/100) × (1 - K/100)
B = 255 × (1 - Y/100) × (1 - K/100)
Example: CMYK(0, 100, 100, 0) → pure red
R = 255 × (1 - 0) × (1 - 0) = 255
G = 255 × (1 - 1) × (1 - 0) = 0
B = 255 × (1 - 1) × (1 - 0) = 0
→ RGB(255, 0, 0) = #FF0000Common Color Values
| Color | CMYK | RGB | Hex |
|---|---|---|---|
| Red | 0, 100, 100, 0 | 255, 0, 0 | #FF0000 |
| Green | 100, 0, 100, 0 | 0, 255, 0 | #00FF00 |
| Blue | 100, 100, 0, 0 | 0, 0, 255 | #0000FF |
| Cyan | 100, 0, 0, 0 | 0, 255, 255 | #00FFFF |
| Magenta | 0, 100, 0, 0 | 255, 0, 255 | #FF00FF |
| Yellow | 0, 0, 100, 0 | 255, 255, 0 | #FFFF00 |
| Black | 0, 0, 0, 100 | 0, 0, 0 | #000000 |
| White | 0, 0, 0, 0 | 255, 255, 255 | #FFFFFF |
When to Use Each Model
- Use RGB/Hex for anything displayed on screen: websites, apps, UI design, digital graphics.
- Use CMYK for print design: business cards, brochures, packaging, anything sent to a commercial printer.
- Use HSL/HSB when you need to adjust hue, saturation, or brightness intuitively in design tools.
When designing for both print and screen, always start in CMYK if print is the primary output. Converting CMYK to RGB for screen is generally safer than the reverse, since the RGB gamut is larger and you may lose color accuracy going from RGB to CMYK.