The main difference between Midnight Blue and Prussian Blue is hue — Midnight Blue is a cool purple, while Prussian Blue is a cool blue. Midnight Blue and Prussian Blue are often confused but have distinct differences in hue, saturation, and tone. Midnight Blue (#191970) and Prussian Blue (#003153) 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.
Prussian Blue is more saturated (100% HSL vs 64%) so it reads as bolder and more memorable at logo scale, while Midnight Blue can feel washed out when printed small.
Midnight Blue hits a 14.85:1 WCAG contrast against white — safer for text-heavy interfaces — where Prussian Blue only reaches 13.43:1 and risks failing AA at small body sizes.
Midnight Blue is a cool-leaning tone that flatters spring/summer collections and warmer skin undertones, while Prussian Blue leans cooler and is better suited to autumn/winter layering.
Midnight Blue is the more muted of the two (64% saturation) and sits more calmly on large wall surfaces, while Prussian Blue's higher chroma can overwhelm a room when used beyond accent pieces.
Midnight Blue (#191970) is a dark, moderately saturated purple with a cool undertone — it feels rich, serious, substantial and balanced in intensity.
Prussian Blue (#003153) is a very dark, vivid blue with a cool undertone — it feels deep, heavy, grounded 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.