Color

#666fd6

#666fd6
hex#666fd6
rgbrgb(102, 111, 214)
hslhsl(235, 58%, 62%)
oklchoklch(0.585 0.156 276.7)
Closest name: Blue Öyster Cult (#5577ee)Relative luminance 0.1905

Colors that go with #666fd6

Charcoal, Sea Green 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 →

#d6cd66

#66a7d6 · #9566d6

#d6666f · #6fd666

Split-complementary

Open in tool →

#d69566 · #a7d666

#d666a7 · #d6cd66 · #66d695

Contrast

#666fd6 as textRatioAAAA largeAAAFix
Aaon white
4.37:1failpassfail
  • AA: use #626bd5 as the text (4.58:1)
  • AAA: use #3a46cb as the text (7.2:1)
  • AA: or shift the background to #0a0a0a (4.53:1)
Aaon black
4.81:1passpassfail
  • AAA: use #8a91e0 as the text (7.21:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #666fd6 as the background.

Brands using this color

Fonts for this mood

#666fd6 reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #666fd6
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 #666fd6 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/666fd6-9e9cc4-df8d4e-241f2d-e9eef1?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