Color

#427bf5

#427bf5
hex#427bf5
rgbrgb(66, 123, 245)
hslhsl(221, 90%, 61%)
oklchoklch(0.611 0.193 263.1)
Closest name: Blue Öyster Cult (#5577ee)Relative luminance 0.2192

Colors that go with #427bf5

Charcoal, Crimson and Copper 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 →

#f5bc42

#42d4f5 · #6342f5

#f5427b · #7bf542

Split-complementary

Open in tool →

#f56342 · #d4f542

#f542d4 · #f5bc42 · #42f563

Contrast

#427bf5 as textRatioAAAA largeAAAFix
Aaon white
3.9:1failpassfail
  • AA: use #2f6df4 as the text (4.55:1)
  • AAA: use #0b4bd5 as the text (7.04:1)
  • AA: or shift the background to #171717 (4.6:1)
Aaon black
5.38:1passpassfail
  • AAA: use #6996f7 as the text (7.31:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #427bf5 as the background.

Brands using this color

Palettes built around it

Fonts for this mood

#427bf5 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #427bf5
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 #427bf5 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/427bf5-9ca4c4-df6b4e-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