Color

#1b3fc0

#1b3fc0
hex#1b3fc0
rgbrgb(27, 63, 192)
hslhsl(227, 75%, 43%)
oklchoklch(0.438 0.205 265.6)
Closest name: Cobalt Blue (#0047ab)Relative luminance 0.0759

Colors that go with #1b3fc0

Charcoal, Sea Green 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 →

#c09c1b

#1b91c0 · #4a1bc0

#c01b3f · #3fc01b

Split-complementary

Open in tool →

#c04a1b · #91c01b

#c01b91 · #c09c1b · #1bc04a

Contrast

#1b3fc0 as textRatioAAAA largeAAAFix
Aaon white
8.34:1passpasspassPasses AAA — no fix needed.
Aaon black
2.52:1failfailfail
  • AA: use #4c6ee6 as the text (4.68:1)
  • AAA: use #7992ec as the text (7.14:1)
  • AA: or shift the background to #bfbfbf (4.53:1)
  • AAA: or shift the background to #ededed (7.12:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #1b3fc0 as the background.

Brands using this color

Fonts for this mood

#1b3fc0 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #1b3fc0
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 #1b3fc0 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/1b3fc0-9ca0c4-df7a4e-221f2d-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