Color

#313d9b

#313d9b
hex#313d9b
rgbrgb(49, 61, 155)
hslhsl(233, 52%, 40%)
oklchoklch(0.41 0.152 272.2)
Closest name: Bluebell (#333399)Relative luminance 0.0636

Colors that go with #313d9b

Charcoal, Sea Green 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.

Real palettes that use #313d9b

Tints & shades

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

Harmonies

Complementary

Open in tool →

#9b8f31

#31729b · #5a319b

#9b313d · #3d9b31

Split-complementary

Open in tool →

#9b5a31 · #729b31

#9b3172 · #9b8f31 · #319b5a

Contrast

#313d9b as textRatioAAAA largeAAAFix
Aaon white
9.25:1passpasspassPasses AAA — no fix needed.
Aaon black
2.27:1failfailfail
  • AA: use #606dcd as the text (4.57:1)
  • AAA: use #8790d9 as the text (7.02:1)
  • AA: or shift the background to #b5b5b5 (4.51:1)
  • AAA: or shift the background to #e0e0e0 (7:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #313d9b as the background.

Brands using this color

No public brand in the corpus uses this exact color yet. Extract a brand to add one.

Fonts for this mood

#313d9b reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #313d9b
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 #313d9b and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/313d9b-9c9cc4-df884e-241f2d-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