Color

#3f4255

#3f4255
hex#3f4255
rgbrgb(63, 66, 85)
hslhsl(232, 15%, 29%)
oklchoklch(0.384 0.033 277.7)
Closest name: Charcoal (#36454f)Relative luminance 0.0561

Colors that go with #3f4255

Steel Blue, Teal and Dark Olive Green 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 →

#55523f

#3f4d55 · #473f55

#553f42 · #42553f

Split-complementary

Open in tool →

#55473f · #4d553f

#553f4d · #55523f · #3f5547

Contrast

#3f4255 as textRatioAAAA largeAAAFix
Aaon white
9.9:1passpasspassPasses AAA — no fix needed.
Aaon black
2.12:1failfailfail
  • AA: use #6f7495 as the text (4.61:1)
  • AAA: use #9296af as the text (7.2:1)
  • AA: or shift the background to #b0b0b0 (4.56:1)
  • AAA: or shift the background to #d9d9d9 (7.01:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3f4255 as the background.

Brands using this color

Fonts for this mood

#3f4255 reads as cool, muted, dark. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3f4255
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 #3f4255 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3f4255-9c9dc4-df864e-231f2d-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