Color

#e51523

#e51523
hex#e51523
rgbrgb(229, 21, 35)
hslhsl(356, 83%, 49%)
oklchoklch(0.586 0.231 26.5)
Closest name: Alarm (#ec0003)Relative luminance 0.1732

Colors that go with #e51523

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 →

#15e5d7

#e5158b · #e56f15

#23e515 · #1523e5

Split-complementary

Open in tool →

#15e56f · #158be5

#8be515 · #15e5d7 · #6f15e5

Contrast

#e51523 as textRatioAAAA largeAAAFix
Aaon white
4.71:1passpassfail
  • AAA: use #b1101b as the text (7.1:1)
Aaon black
4.46:1failpassfail
  • AA: use #e91624 as the text (4.6:1)
  • AAA: use #f16a73 as the text (7.05:1)
  • AA: or shift the background to #fafafa (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 #e51523 as the background.

Brands using this color

Fonts for this mood

#e51523 reads as warm, vivid, playful. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #e51523
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 #e51523 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/e51523-c49e9c-62cb91-2d241f-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