Color

#666dd6

#666dd6
hex#666dd6
rgbrgb(102, 109, 214)
hslhsl(236, 58%, 62%)
oklchoklch(0.581 0.158 277.4)
Closest name: Blue Öyster Cult (#5577ee)Relative luminance 0.1862

Colors that go with #666dd6

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 →

#d6cf66

#66a6d6 · #9766d6

#d6666d · #6dd666

Split-complementary

Open in tool →

#d69766 · #a6d666

#d666a6 · #d6cf66 · #66d697

Contrast

#666dd6 as textRatioAAAA largeAAAFix
Aaon white
4.45:1failpassfail
  • AA: use #626ad5 as the text (4.62:1)
  • AAA: use #3e47cc as the text (7.05:1)
  • AA: or shift the background to #080808 (4.5:1)
Aaon black
4.72:1passpassfail
  • AAA: use #8a90e0 as the text (7.15:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #666dd6 as the background.

Brands using this color

Fonts for this mood

#666dd6 reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #666dd6
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 #666dd6 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/666dd6-9e9cc4-df8f4e-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