Color

#b00311

#b00311
hex#b00311
rgbrgb(176, 3, 17)
hslhsl(355, 97%, 35%)
oklchoklch(0.477 0.193 27.2)
Closest name: All Systems Red (#b30103)Relative luminance 0.0934

Colors that go with #b00311

Royal Blue, Teal 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 →

#03b0a1

#b00368 · #b04b03

#11b003 · #0311b0

Split-complementary

Open in tool →

#03b04b · #0368b0

#68b003 · #03b0a1 · #4b03b0

Contrast

#b00311 as textRatioAAAA largeAAAFix
Aaon white
7.32:1passpasspassPasses AAA — no fix needed.
Aaon black
2.87:1failfailfail
  • AA: use #ec0417 as the text (4.6:1)
  • AAA: use #fd6370 as the text (7.2:1)
  • AA: or shift the background to #cccccc (4.56:1)
  • AAA: or shift the background to #fafafa (7.02:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #b00311 as the background.

Brands using this color

Fonts for this mood

#b00311 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #b00311
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 #b00311 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/b00311-c49e9c-62cb8f-2d241f-f1e9ee?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