Color

#666bb2

#666bb2
hex#666bb2
rgbrgb(102, 107, 178)
hslhsl(236, 33%, 55%)
oklchoklch(0.555 0.11 279.1)
Closest name: Loch Ness (#5f6db0)Relative luminance 0.1655

Colors that go with #666bb2

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 →

#b2ad66

#6691b2 · #8766b2

#b2666b · #6bb266

Split-complementary

Open in tool →

#b28766 · #91b266

#b26691 · #b2ad66 · #66b287

Contrast

#666bb2 as textRatioAAAA largeAAAFix
Aaon white
4.87:1passpassfail
  • AAA: use #4d5299 as the text (7.04:1)
Aaon black
4.31:1failpassfail
  • AA: use #6a6fb4 as the text (4.55:1)
  • AAA: use #8f93c7 as the text (7.17:1)
  • AA: or shift the background to #f7f7f7 (4.55:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #666bb2 as the background.

Brands using this color

mcpConnect your agent — build around #666bb2
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 #666bb2 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/666bb2-9e9cc4-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