Ink & Paper
Open in tool →Two greys and one ink-blue link color: the palette of a well-set book page.
Color
#243ea8
#243ea8
hex
#243ea8rgb
rgb(36, 62, 168)hsl
hsl(228, 65%, 40%)oklch
oklch(0.417 0.172 267.4)Closest name: Cobalt Blue (#0047ab)Relative luminance 0.0665
Colors that go with #243ea8
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.
Charcoal #36454f
neutralshippedCharcoal is the text near-black for #243ea8: softer than #000 and cool enough to feel like part of the same palette.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #243ea8 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Steel Blue #4682b4
analogousshippedSteel Blue is #243ea8's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Amber #ffbf00
shippedAmber is paired with #243ea8 in 4 real palettes, including Warner Bros.'s brand system and Walmart's brand system, as the accent.
Blue #0000ff
shipped8 real palettes, including Procter & Gamble's brand system and CVS's brand system put Blue beside #243ea8, as the supporting colour.
Cornflower Blue #6495ed
shippedDesigners have shipped Cornflower Blue with #243ea8: 5 real palettes, including Blue Mono and Gopro's brand system, as the supporting colour.
Crimson #dc143c
shippedCrimson is paired with #243ea8 in 13 real palettes, including Walgreens's brand system and Behance's brand system, as the lead colour.
Dodger Blue #1e90ff
shippedDesigners have shipped Dodger Blue with #243ea8: 4 real palettes, including Coursera's brand system and Absolut's brand system, as the supporting colour.
Real palettes that use #243ea8
Tints & shades
Harmonies
Contrast
| #243ea8 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 9.01:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.33:1 | fail | fail | fail |
Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #243ea8 as the background.
Brands using this color
Palettes built around it
Cobalt Pop
Open in tool →One deep cobalt and one hot pink on white — a two-accent system for launches and campaign pages that need punch.
Blue Mono
Open in tool →One blue at four lightnesses — monochromatic in the colour-theory sense; the deep step is the text, the pale step the surface tint.
Fonts for this mood
#243ea8 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #243ea8
live endpointPoint 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.
endpoint
https://mcp.brandsweets.com/colors/mcpclaude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt
›analyze #243ea8 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/243ea8-9c9fc4-df7c4e-231f2d-e9eff1?lock=0&style=vibrantWant the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.
Machine-readable: color.md