Color

#1b4bc5

#1b4bc5
hex#1b4bc5
rgbrgb(27, 75, 197)
hslhsl(223, 76%, 44%)
oklchoklch(0.465 0.197 263.9)
Closest name: Cobalt Blue (#0047ab)Relative luminance 0.093

Colors that go with #1b4bc5

Charcoal, Steel Blue and Amber 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 →

#c5951b

#1ba1c5 · #401bc5

#c51b4b · #4bc51b

Split-complementary

Open in tool →

#c5401b · #a1c51b

#c51ba1 · #c5951b · #1bc540

Contrast

#1b4bc5 as textRatioAAAA largeAAAFix
Aaon white
7.34:1passpasspassPasses AAA — no fix needed.
Aaon black
2.86:1failfailfail
  • AA: use #3e6de5 as the text (4.52:1)
  • AAA: use #6f93eb as the text (7.05:1)
  • AA: or shift the background to #cccccc (4.57:1)
  • AAA: or shift the background to #fafafa (7.04:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #1b4bc5 as the background.

Brands using this color

Fonts for this mood

#1b4bc5 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #1b4bc5
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 #1b4bc5 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/1b4bc5-9ca3c4-df704e-211f2d-e9eff1?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