Ink & Paper
Open in tool →Two greys and one ink-blue link color: the palette of a well-set book page.
Color
#243ca8
#243ca8
hex
#243ca8rgb
rgb(36, 60, 168)hsl
hsl(229, 65%, 40%)oklch
oklch(0.413 0.175 267.8)Closest name: Cobalt Blue (#0047ab)Relative luminance 0.0643
Colors that go with #243ca8
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 #243ca8: softer than #000 and cool enough to feel like part of the same palette.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #243ca8 — 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 #243ca8's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Blue #0000ff
shippedBlue is paired with #243ca8 in 6 real palettes, including Procter & Gamble's brand system and CVS's brand system, as the supporting colour — a combination designers have actually shipped, not a computed rotation.
Cornflower Blue #6495ed
shippedCornflower Blue is paired with #243ca8 in 4 real palettes, including Blue Mono and Peacock's brand system, as the supporting colour — a combination designers have actually shipped, not a computed rotation.
Crimson #dc143c
shippedCrimson is paired with #243ca8 in 9 real palettes, including Behance's brand system and Chase's brand system, as the accent — a combination designers have actually shipped, not a computed rotation.
Firebrick #b22222
shippedFirebrick is paired with #243ca8 in 4 real palettes, including Nissan's brand system and Datadog's brand system, as the supporting colour — a combination designers have actually shipped, not a computed rotation.
Midnight Blue #191970
shippedMidnight Blue is paired with #243ca8 in 12 real palettes, including Blue Mono and Fintech Trust, as the text colour against it — a combination designers have actually shipped, not a computed rotation.
Real palettes that use #243ca8
Tints & shades
Harmonies
Contrast
| #243ca8 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 9.18:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.29:1 | 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 #243ca8 as the background.
Brands using this color
No public brand in the corpus uses this exact color yet. Extract a brand to add one.
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
#243ca8 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #243ca8
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 #243ca8 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/243ca8-9c9fc4-df7e4e-231f2d-e9eef1?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