Color

#b30009

#b30009
hex#b30009
rgbrgb(179, 0, 9)
hslhsl(357, 100%, 35%)
oklchoklch(0.482 0.197 28.1)
Closest name: All Systems Red (#b30103)Relative luminance 0.096

Colors that go with #b30009

Royal Blue, Steel Blue and Teal 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 →

#00b3aa

#b30062 · #b35000

#09b300 · #0009b3

Split-complementary

Open in tool →

#00b350 · #0062b3

#62b300 · #00b3aa · #5000b3

Contrast

#b30009 as textRatioAAAA largeAAAFix
Aaon white
7.19:1passpasspassPasses AAA — no fix needed.
Aaon black
2.92:1failfailfail
  • AA: use #eb000c as the text (4.54:1)
  • AAA: use #ff6169 as the text (7.17:1)
  • AA: or shift the background to #cfcfcf (4.62:1)
  • AAA: or shift the background to #fcfcfc (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 #b30009 as the background.

Brands using this color

Fonts for this mood

#b30009 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #b30009
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 #b30009 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/b30009-c49f9c-62cb93-2d251f-f1e9ed?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