The main difference between Navy and Indigo is hue — Navy is a cool blue, while Indigo is a warm-leaning purple. Navy (#001F3F) is a very dark blue named after military uniforms, while Indigo (#4B0082) is a dark violet-purple named after the plant dye. Navy is pure dark blue; indigo is distinctly purple-leaning.
Four real design scenarios, with the recommended pick based on hue, saturation, and WCAG contrast.
Navy is more saturated (100% HSL vs 100%) so it reads as bolder and more memorable at logo scale, while Indigo can feel washed out when printed small.
Navy hits a 16.56:1 WCAG contrast against white — safer for text-heavy interfaces — where Indigo only reaches 12.95:1 and risks failing AA at small body sizes.
Indigo is a warm tone that flatters spring/summer collections and warmer skin undertones, while Navy leans cooler and is better suited to autumn/winter layering.
Navy is the more muted of the two (100% saturation) and sits more calmly on large wall surfaces, while Indigo's higher chroma can overwhelm a room when used beyond accent pieces.
Navy (RGB 0,31,63) is an extremely dark pure blue at L=12% — the uniform color of the British Royal Navy since 1748.
Indigo (RGB 75,0,130) is a dark purple-blue at L=25% — named after the ancient plant dye Indigofera tinctoria, and one of Newton's 7 rainbow colors.
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.