Color

#3f555f

#3f555f
hex#3f555f
rgbrgb(63, 85, 95)
hslhsl(199, 20%, 31%)
oklchoklch(0.435 0.032 227.6)
Closest name: All Nighter (#455454)Relative luminance 0.0838

Colors that go with #3f555f

Sienna, Blue and Cadet Blue 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.

Real palettes that use #3f555f

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#5f493f

#3f5f59 · #3f455f

#5f3f55 · #555f3f

Split-complementary

Open in tool →

#5f3f45 · #5f593f

#593f5f · #5f493f · #455f3f

Contrast

#3f555f as textRatioAAAA largeAAAFix
Aaon white
7.85:1passpasspassPasses AAA — no fix needed.
Aaon black
2.68:1failfailfail
  • AA: use #5c7b8a as the text (4.66:1)
  • AAA: use #7e9ca9 as the text (7.22:1)
  • AA: or shift the background to #c7c7c7 (4.64:1)
  • AAA: or shift the background to #f2f2f2 (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 #3f555f as the background.

Brands using this color

No public brand in the corpus uses this exact color yet. Extract a brand to add one.

mcpConnect your agent — build around #3f555f
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 #3f555f and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3f555f-9cb3c4-df4e66-1f232d-e9f1f0?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