Color

#51abfb

#51abfb
hex#51abfb
rgbrgb(81, 171, 251)
hslhsl(208, 96%, 65%)
oklchoklch(0.721 0.145 248.1)
Closest name: Cerulean (#55aaee)Relative luminance 0.3784

Tints & shades

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

Harmonies

Complementary

Open in tool →

#fba050

#50fbf6 · #5056fb

#fb50ab · #abfb50

Split-complementary

Open in tool →

#fb5056 · #fbf650

#f650fb · #fba050 · #56fb50

Contrast

#51abfb as textRatioAAAA largeAAAFix
Aaon white
2.45:1failfailfail
  • AA: use #0475d7 as the text (4.63:1)
  • AAA: use #0357a0 as the text (7.3:1)
  • AA: or shift the background to #3b3b3b (4.57:1)
  • AAA: or shift the background to #1a1a1a (7.1:1)
Aaon black
8.57:1passpasspassPasses AAA — no fix needed.

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #51abfb as the background.

Brands using this color

Palettes built around it

Fonts for this mood

#51abfb reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #51abfb
live endpoint

Point any MCP client at the shared colors endpoint and your agent gets the same engine as this page — generate_palette, check_contrast, analyze_color — read-only, no key. Every palette it proposes comes with a /palettes/new/… link: open it, lock what you like, paste the link back.

endpointhttps://mcp.brandsweets.com/colors/mcp
claude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt

analyze #51abfb and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/51abfb-9cadc4-df4e51-1f212d-e9f1f1?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