The main difference between Slate Grey and Gunmetal is brightness and saturation: both are blue shades, but Slate Grey is lighter. Slate Grey (#708090) has an HSL of 210°, 13%, 50%, whereas Gunmetal (#2A3439) sits at 200°, 15%, 19%.
Four real design scenarios, with the recommended pick based on hue, saturation, and WCAG contrast.
Gunmetal is more saturated (15% HSL vs 13%) so it reads as bolder and more memorable at logo scale, while Slate Grey can feel washed out when printed small.
Gunmetal hits a 12.74:1 WCAG contrast against white — safer for text-heavy interfaces — where Slate Grey only reaches 4.05:1 and risks failing AA at small body sizes.
Slate Grey is a cool-leaning tone that flatters spring/summer collections and warmer skin undertones, while Gunmetal leans cooler and is better suited to autumn/winter layering.
Slate Grey is the more muted of the two (13% saturation) and sits more calmly on large wall surfaces, while Gunmetal's higher chroma can overwhelm a room when used beyond accent pieces.
Slate Grey (#708090) is a medium, near-neutral blue with a cool undertone — it feels balanced, versatile and desaturated and restrained.
Gunmetal (#2A3439) is a very dark, muted blue with a cool undertone — it feels deep, heavy, grounded and subdued, sophisticated.
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.
Each color has a dedicated page with shades, tints, CSS name, pairings, and color psychology.