Color

#b3001b

#b3001b
hex#b3001b
rgbrgb(179, 0, 27)
hslhsl(351, 100%, 35%)
oklchoklch(0.483 0.196 25)
Closest name: All Systems Red (#b30103)Relative luminance 0.0966

Colors that go with #b3001b

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 →

#00b398

#b30074 · #b33e00

#1bb300 · #001bb3

Split-complementary

Open in tool →

#00b33e · #0074b3

#74b300 · #00b398 · #3e00b3

Contrast

#b3001b as textRatioAAAA largeAAAFix
Aaon white
7.16:1passpasspassPasses AAA — no fix needed.
Aaon black
2.93:1failfailfail
  • AA: use #eb0023 as the text (4.56:1)
  • AAA: use #ff5c74 as the text (7.04:1)
  • AA: or shift the background to #cfcfcf (4.6:1)
  • AAA: or shift the background to #ffffff (7.16:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #b3001b as the background.

Brands using this color

Fonts for this mood

#b3001b reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #b3001b
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 #b3001b and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/b3001b-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