#0366D1
Closest named color: Royal Blue (#4169E1). oklch(52.6% 0.183 256.7), rgb(3, 102, 209).
Aa
White text reads best on this color (5.49:1).
About this color
#0366D1 is a medium-dark, vivid blue. In OKLCH its lightness is 53%, its chroma 0.183 and its hue 257°. Its hue sits on the cool side of the wheel. The nearest named color is Royal Blue (#4169E1), ΔE 0.046 away. White text reads best on it, at 5.49:1.
| Hue family | Blues |
| Lightness | medium-dark (53%) |
| Chroma | vivid (0.183) |
| Temperature | cool |
| Nearest name | Royal Blue (#4169E1) |
| Black text | 3.82:1 |
| White text | 5.49:1 |
Values
| HEX | #0366D1 |
| RGB | rgb(3, 102, 209) |
| HSL | hsl(211, 97%, 42%) |
| OKLCH | oklch(52.6% 0.183 256.7) |
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 #0366D1 | 5.49:1 | AA | Lc -81.9 | Fine for body text |
| Black text on #0366D1 | 3.82:1 | AA large text | Lc 27.5 | Dividers and decoration only |
| #0366D1 text on white | 5.49:1 | AA | Lc 76.6 | Fine for body text |
| #0366D1 text on black | 3.82:1 | AA large text | Lc -25.1 | 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
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#E0EBFA
oklch(93.6% 0.024 256.1)
-
Step 200
200
#C6DBF8
oklch(88.5% 0.046 256.5)
-
Step 300
300
#9FC3F6
oklch(80.9% 0.082 257.1)
-
Step 400
400
#69A2F2
oklch(70.7% 0.132 257)
-
Step 500
500
#3D88ED
oklch(63.1% 0.169 256.9)
-
Step 600
600 (this color)
#0366D1
oklch(52.6% 0.183 256.7)
-
Step 700
700
#035CBE
oklch(49% 0.171 256.8)
-
Step 800
800
#0B4C9A
oklch(42.7% 0.141 256.8)
-
Step 900
900
#14407A
oklch(37.6% 0.11 256.9)
-
Step 950
950
#0D2648
oklch(27% 0.07 257)
#0366D1 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) | #1872D5 | 0.034 |
| Deuteranopia (no green cones) | #0061CF | 0.013 |
| Tritanopia (no blue cones) | #008192 | 0.138 |
| Achromatopsia (no color) | #696969 | 0.183 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #0366D1
#0366D1
oklch(52.6% 0.183 256.7)
- #8E6100
#8E6100
oklch(52.7% 0.11 77.1)
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 #0366D1, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Royal Blue #4169E1 ΔE 0.046
- Azul #1D5DEC ΔE 0.048
- Cerulean Blue #056EEE ΔE 0.048
- Mid Blue #276AB3 ΔE 0.051
- Warm Blue #4B57DB ΔE 0.058
- Neon Blue #4361EE ΔE 0.060
- Bright Blue #0165FC ΔE 0.066
- Windows Blue #3778BF ΔE 0.068
Use #0366D1 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.