Color

#b52121

#b52121
hex#b52121
rgbrgb(181, 33, 33)
hslhsl(0, 69%, 42%)
oklchoklch(0.502 0.183 27)
Closest name: firebrick (#b22222)Relative luminance 0.1102

Colors that go with #b52121

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 →

#21b5b5

#b5216b · #b56b21

#21b521 · #2121b5

Split-complementary

Open in tool →

#21b56b · #216bb5

#6bb521 · #21b5b5 · #6b21b5

Contrast

#b52121 as textRatioAAAA largeAAAFix
Aaon white
6.55:1passpassfail
  • AAA: use #ac2020 as the text (7.04:1)
Aaon black
3.2:1failpassfail
  • AA: use #da3434 as the text (4.52:1)
  • AAA: use #e67575 as the text (7.17:1)
  • AA: or shift the background to #d6d6d6 (4.51:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #b52121 as the background.

Brands using this color

Palettes built around it

Fonts for this mood

#b52121 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #b52121
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 #b52121 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/b52121-c4a19c-62cb98-2d251f-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