Color

#3951d5

#3951d5
hex#3951d5
rgbrgb(57, 81, 213)
hslhsl(231, 65%, 53%)
oklchoklch(0.501 0.203 269.5)
Closest name: Arcane Brew (#5260e1)Relative luminance 0.1156

Colors that go with #3951d5

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.

Real palettes that use #3951d5

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#d5be39

#399fd5 · #7039d5

#d53951 · #51d539

Split-complementary

Open in tool →

#d57039 · #9fd539

#d5399f · #d5be39 · #39d570

Contrast

#3951d5 as textRatioAAAA largeAAAFix
Aaon white
6.34:1passpassfail
  • AAA: use #2d45d2 as the text (7.26:1)
Aaon black
3.31:1failpassfail
  • AA: use #576bdb as the text (4.53:1)
  • AAA: use #8190e4 as the text (7.04:1)
  • AA: or shift the background to #dbdbdb (4.58:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3951d5 as the background.

Brands using this color

Fonts for this mood

#3951d5 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3951d5
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 #3951d5 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3951d5-9c9ec4-df834e-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