The main difference between Slate Blue and Periwinkle is brightness and saturation: both are purple shades, but Periwinkle is lighter and Periwinkle is more saturated. Slate Blue and Periwinkle are often confused but have distinct differences in hue, saturation, and tone. Slate Blue (#6A5ACD) and Periwinkle (#CCCCFF) 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.
Periwinkle is more saturated (100% HSL vs 53%) so it reads as bolder and more memorable at logo scale, while Slate Blue can feel washed out when printed small.
Slate Blue hits a 5.31:1 WCAG contrast against white — safer for text-heavy interfaces — where Periwinkle only reaches 1.54:1 and risks failing AA at small body sizes.
Periwinkle is a cool-leaning tone that flatters spring/summer collections and warmer skin undertones, while Slate Blue leans cooler and is better suited to autumn/winter layering.
Slate Blue is the more muted of the two (53% saturation) and sits more calmly on large wall surfaces, while Periwinkle's higher chroma can overwhelm a room when used beyond accent pieces.
Slate Blue (#6A5ACD) is a medium, moderately saturated purple with a cool undertone — it feels balanced, versatile and balanced in intensity.
Periwinkle (#CCCCFF) is a very light, vivid purple with a cool undertone — it feels pale, delicate, gentle and bright, energetic, eye-catching.
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.