Color

#b21028

#b21028
hex#b21028
rgbrgb(178, 16, 40)
hslhsl(351, 84%, 38%)
oklchoklch(0.487 0.189 22.5)
Closest name: firebrick (#b22222)Relative luminance 0.0999

Colors that go with #b21028

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 →

#10b29a

#b21079 · #b24810

#28b210 · #1028b2

Split-complementary

Open in tool →

#10b248 · #1079b2

#79b210 · #10b29a · #4810b2

Contrast

#b21028 as textRatioAAAA largeAAAFix
Aaon white
7.01:1passpasspassPasses AAA — no fix needed.
Aaon black
3:1failfailfail
  • AA: use #e61433 as the text (4.51:1)
  • AAA: use #f2697d as the text (7.09:1)
  • AA: or shift the background to #d1d1d1 (4.59:1)
  • AAA: or shift the background to #ffffff (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 #b21028 as the background.

Brands using this color

Fonts for this mood

#b21028 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #b21028
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 #b21028 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/b21028-c49c9e-62cb89-2d231f-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