Color

#f31215

#f31215
hex#f31215
rgbrgb(243, 18, 21)
hslhsl(359, 90%, 51%)
oklchoklch(0.61 0.244 28.4)
Closest name: Assassin’s Red (#f60206)Relative luminance 0.1954

Colors that go with #f31215

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 →

#12f3ef

#f31286 · #f37e12

#15f312 · #1215f3

Split-complementary

Open in tool →

#12f37e · #1286f3

#86f312 · #12f3ef · #7e12f3

Contrast

#f31215 as textRatioAAAA largeAAAFix
Aaon white
4.28:1failpassfail
  • AA: use #ed0c10 as the text (4.51:1)
  • AAA: use #b3090c as the text (7.09:1)
  • AA: or shift the background to #0d0d0d (4.54:1)
Aaon black
4.91:1passpassfail
  • AAA: use #f7696b as the text (7.19:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #f31215 as the background.

Brands using this color

Fonts for this mood

#f31215 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #f31215
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 #f31215 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/f31215-c4a09c-62cb96-2d251f-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