The main difference between Steel Blue and Slate is brightness and saturation: both are blue shades, but they share similar brightness and Steel Blue is more saturated. Steel Blue and Slate are often confused but have distinct differences in hue, saturation, and tone. Steel Blue (#4682B4) and Slate (#708090) each suit different design contexts — understanding their differences helps you choose the right color for your project.
Four real design scenarios, with the recommended pick based on hue, saturation, and WCAG contrast.
Steel Blue is more saturated (44% HSL vs 13%) so it reads as bolder and more memorable at logo scale, while Slate can feel washed out when printed small.
Steel Blue hits a 4.11:1 WCAG contrast against white — safer for text-heavy interfaces — where Slate only reaches 4.05:1 and risks failing AA at small body sizes.
Slate is a cool-leaning tone that flatters spring/summer collections and warmer skin undertones, while Steel Blue leans cooler and is better suited to autumn/winter layering.
Slate is the more muted of the two (13% saturation) and sits more calmly on large wall surfaces, while Steel Blue's higher chroma can overwhelm a room when used beyond accent pieces.
Steel Blue (#4682B4) is a medium, moderately saturated blue with a cool undertone — it feels balanced, versatile and balanced in intensity.
Slate (#708090) is a medium, near-neutral blue with a cool undertone — it feels balanced, versatile and desaturated and restrained.
Text legibility depends on the contrast ratio between foreground and background. WCAG 2.1 AA requires at least 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1. Use these numbers to choose accessible combinations for your design.