Color

#f3121d

#f3121d
hex#f3121d
rgbrgb(243, 18, 29)
hslhsl(357, 90%, 51%)
oklchoklch(0.61 0.243 27.5)
Closest name: Assassin’s Red (#f60206)Relative luminance 0.1958

Colors that go with #f3121d

Charcoal, Royal Blue and Steel Blue 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 →

#12f3e7

#f3128d · #f37712

#1df312 · #121df3

Split-complementary

Open in tool →

#12f377 · #128df3

#8df312 · #12f3e7 · #7712f3

Contrast

#f3121d as textRatioAAAA largeAAAFix
Aaon white
4.27:1failpassfail
  • AA: use #e90c17 as the text (4.64:1)
  • AAA: use #b30912 as the text (7.08:1)
  • AA: or shift the background to #0d0d0d (4.55:1)
Aaon black
4.92:1passpassfail
  • AAA: use #f76970 as the text (7.21:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #f3121d as the background.

Brands using this color

Fonts for this mood

#f3121d reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #f3121d
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 #f3121d and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/f3121d-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