Color

#303eb5

#303eb5
hex#303eb5
rgbrgb(48, 62, 181)
hslhsl(234, 58%, 45%)
oklchoklch(0.434 0.186 270.9)
Closest name: Cobalt Blue (#0047ab)Relative luminance 0.0741

Colors that go with #303eb5

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.

Tints & shades

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

Harmonies

Complementary

Open in tool →

#b5a830

#3080b5 · #6530b5

#b5303e · #3eb530

Split-complementary

Open in tool →

#b56530 · #80b530

#b53080 · #b5a830 · #30b565

Contrast

#303eb5 as textRatioAAAA largeAAAFix
Aaon white
8.46:1passpasspassPasses AAA — no fix needed.
Aaon black
2.48:1failfailfail
  • AA: use #626dd5 as the text (4.67:1)
  • AAA: use #868fdf as the text (7.01:1)
  • AA: or shift the background to #bdbdbd (4.5:1)
  • AAA: or shift the background to #ebebeb (7.1:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #303eb5 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

#303eb5 reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #303eb5
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 #303eb5 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/303eb5-9d9cc4-df8a4e-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