Cobalt Blue hex code

Cobalt Blue

#0047ab
hex#0047ab
rgbrgb(0, 71, 171)
hslhsl(215, 100%, 34%)
oklchoklch(0.428 0.172 259.7)
Relative luminance 0.0745

Cobalt Blue is a deep, highly saturated blue — #0047ab, rgb(0, 71, 171), hue 215° at 100% saturation. The colours that go with cobalt blue are Charcoal, Crimson and Steel Blue — each with the reason below, and the real palettes that pair them. As text it passes WCAG AA on white at 8.44:1, so it can be a body colour, not just a fill. 2 public brands use it in a role token.

Colors that go with Cobalt Blue

Charcoal, Crimson and Steel Blue lead the list. Each partner is a real named colour with the reason it works — a wheel relationship, a neutral that carries it, or a pairing lifted from a palette or brand system that actually shipped — and every pair opens in the palette tool.

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#ad6500

#009fad · #0e00ad

#ad0048 · #48ad00

Split-complementary

Open in tool →

#ad0e00 · #9fad00

#ad009f · #ad6500 · #00ad0e

Contrast

Cobalt Blue as textRatioAAAA largeAAAFix
Aaon white
8.44:1passpasspassPasses AAA — no fix needed.
Aaon black
2.49:1failfailfail
  • AA: use #006aff as the text (4.51:1)
  • AAA: use #4d97ff as the text (7.19:1)
  • AA: or shift the background to #bfbfbf (4.59:1)
  • AAA: or shift the background to #ebebeb (7.08:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with Cobalt Blue as the background.

Brands using this color

Fonts for this mood

Cobalt Blue reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around Cobalt Blue
live endpoint

Point any MCP client at the shared colors endpoint and your agent gets the same engine as this page — direct_palette, edit_direction, check_palette, check_contrast — read-only, no key. Every direction it proposes comes with a /colors/d/… link: open it, lock what you like, paste the link back, and the agent edits rather than re-rolls.

endpointhttps://mcp.brandsweets.com/colors/mcp
claude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt

analyze #0047ab and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/0047ab-9ca8c4-df5d4e-201f2d-e9f0f1?lock=0&style=vibrant

Want the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.

Machine-readable: color.md