Color

#1b57da

#1b57da
hex#1b57da
rgbrgb(27, 87, 218)
hslhsl(221, 78%, 48%)
oklchoklch(0.506 0.21 262.8)
Closest name: Denim (#1560bd)Relative luminance 0.1211

Colors that go with #1b57da

Charcoal, Crimson 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 →

#da9d1b

#1bb7da · #3e1bda

#da1b57 · #57da1b

Split-complementary

Open in tool →

#da3e1b · #b7da1b

#da1bb7 · #da9d1b · #1bda3e

Contrast

#1b57da as textRatioAAAA largeAAAFix
Aaon white
6.14:1passpassfail
  • AAA: use #184ec3 as the text (7.2:1)
Aaon black
3.42:1failpassfail
  • AA: use #376fe6 as the text (4.58:1)
  • AAA: use #6e96ed as the text (7.25:1)
  • AA: or shift the background to #dedede (4.56:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #1b57da as the background.

Brands using this color

Fonts for this mood

#1b57da reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #1b57da
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 #1b57da and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/1b57da-9ca4c4-df6b4e-211f2d-e9eff1?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