Color

#3d4057

#3d4057
hex#3d4057
rgbrgb(61, 64, 87)
hslhsl(233, 18%, 29%)
oklchoklch(0.378 0.039 278.6)
Closest name: Charcoal (#36454f)Relative luminance 0.0535

Colors that go with #3d4057

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 →

#57543d

#3d4d57 · #473d57

#573d40 · #40573d

Split-complementary

Open in tool →

#57473d · #4d573d

#573d4d · #57543d · #3d5747

Contrast

#3d4057 as textRatioAAAA largeAAAFix
Aaon white
10.15:1passpasspassPasses AAA — no fix needed.
Aaon black
2.07:1failfailfail
  • AA: use #6f749b as the text (4.65:1)
  • AAA: use #9094b2 as the text (7.06:1)
  • AA: or shift the background to #adadad (4.52:1)
  • AAA: or shift the background to #d9d9d9 (7.19:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3d4057 as the background.

Brands using this color

Fonts for this mood

#3d4057 reads as cool, muted, dark. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3d4057
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 #3d4057 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3d4057-9c9cc4-df884e-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