Color

#3a51bb

#3a51bb
hex#3a51bb
rgbrgb(58, 81, 187)
hslhsl(229, 53%, 48%)
oklchoklch(0.48 0.169 269.7)
Closest name: Blasphemous Blue (#3356aa)Relative luminance 0.1037

Colors that go with #3a51bb

Charcoal, Sea Green and Amber 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 →

#bba33a

#3a92bb · #633abb

#bb3a51 · #51bb3a

Split-complementary

Open in tool →

#bb633a · #92bb3a

#bb3a92 · #bba33a · #3abb63

Contrast

#3a51bb as textRatioAAAA largeAAAFix
Aaon white
6.83:1passpassfail
Aaon black
3.07:1failpassfail
  • AA: use #5b70cd as the text (4.64:1)
  • AAA: use #8292d9 as the text (7.06:1)
  • AA: or shift the background to #d4d4d4 (4.61:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3a51bb as the background.

Brands using this color

Fonts for this mood

#3a51bb reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3a51bb
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 #3a51bb and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3a51bb-9c9fc4-df7e4e-231f2d-e9eef1?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