#366ECB
Closest named color: Windows Blue (#3778BF). oklch(55% 0.156 260), rgb(54, 110, 203).
Aa
White text reads best on this color (4.94:1).
About this color
#366ECB is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.156 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.036 away. White text reads best on it, at 4.94:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.156) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.24:1 |
| White text | 4.94:1 |
Values
| HEX | #366ECB |
| RGB | rgb(54, 110, 203) |
| HSL | hsl(217, 59%, 50%) |
| OKLCH | oklch(55% 0.156 260) |
Contrast
WCAG 2 contrast ratios are the conformance target: AA needs 4.5:1 for body text and 3:1 for large text, AAA needs 7:1. APCA Lc values are supplementary guidance from the WCAG 3 drafts.
| Pair | WCAG 2 | Result | APCA | APCA guidance |
|---|---|---|---|---|
| White text on #366ECB | 4.94:1 | AA | Lc -79.3 | Fine for body text |
| Black text on #366ECB | 4.24:1 | AA large text | Lc 30.2 | Non-text elements, placeholder text |
| #366ECB text on white | 4.94:1 | AA | Lc 73.8 | Content text, not long reading |
| #366ECB text on black | 4.24:1 | AA large text | Lc -27.9 | Dividers and decoration only |
Tints and shades
A 50–950 scale built in OKLCH: the hue is held, lightness follows a Tailwind v4-like curve, and every step is kept inside the sRGB gamut. This color sits at step 600.
-
Step 50
50
#F2F6FC
oklch(97.2% 0.009 258.3)
-
Step 100
100
#E2EAF8
oklch(93.5% 0.021 261.8)
-
Step 200
200
#CADAF4
oklch(88.4% 0.04 260.1)
-
Step 300
300
#A6C2EF
oklch(80.9% 0.071 259.8)
-
Step 400
400
#77A1E7
oklch(70.7% 0.113 260.3)
-
Step 500
500
#5388DF
oklch(63.1% 0.143 259.8)
-
Step 600
600 (this color)
#366ECB
oklch(55% 0.156 260)
-
Step 700
700
#2A5DB1
oklch(49% 0.145 259.9)
-
Step 800
800
#244C90
oklch(42.6% 0.121 260.3)
-
Step 900
900
#224073
oklch(37.7% 0.095 260.3)
-
Step 950
950
#142643
oklch(27% 0.059 259.5)
#366ECB with color blindness
Simulated with the Machado et al. (2009) model. ΔE is how far the color moves: below about 0.02 you would not notice a change.
| Vision | Seen as | Shift (ΔE) |
|---|---|---|
| Protanopia (no red cones) | #3D77CF | 0.026 |
| Deuteranopia (no green cones) | #1C6AC9 | 0.022 |
| Tritanopia (no blue cones) | #008492 | 0.124 |
| Achromatopsia (no color) | #707070 | 0.156 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #366ECB
#366ECB
oklch(55% 0.156 260)
- #946900
#946900
oklch(55.1% 0.114 80.3)
Analogous
Neighbouring hues, 30° either side.
Split complementary
The two hues beside the complement (150° and 210°).
Triadic
Three hues spaced 120° apart.
Palettes with this color
Curated palettes that contain a color within ΔE 0.04 (OKLab) of #366ECB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.036
- Royal Blue #4169E1 ΔE 0.039
- Mid Blue #276AB3 ΔE 0.041
- French Blue #436BAD ΔE 0.047
- Cerulean Blue #056EEE ΔE 0.057
- Flat Blue #3C73A8 ΔE 0.059
- Nice Blue #107AB0 ΔE 0.061
- Dark Periwinkle #665FD1 ΔE 0.064
Use #366ECB in your product
Turn it into light and dark UI roles checked for contrast, then export to Tailwind v4, shadcn/ui, CSS or design tokens.