The main difference between Slate and Off Black is hue — Slate is a cool blue, while Off Black is a neutral near-black. Slate and Off Black are often confused but have distinct differences in hue, saturation, and tone. Slate (#708090) and Off Black (#1C1C1C) 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.
Slate is more saturated (13% HSL vs 0%) so it reads as bolder and more memorable at logo scale, while Off Black can feel washed out when printed small.
Off Black hits a 17.04:1 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 Off Black leans cooler and is better suited to autumn/winter layering.
Off Black is the more muted of the two (0% saturation) and sits more calmly on large wall surfaces, while Slate's higher chroma can overwhelm a room when used beyond accent pieces.
Slate (#708090) is a medium, near-neutral blue with a cool undertone — it feels balanced, versatile and desaturated and restrained.
Off Black (#1C1C1C) is a very dark, near-neutral near-black with a neutral undertone — it feels deep, heavy, grounded 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.