Colour reference
Signal Blue
#4287f5
A bright, friendly blue that reads well on dark and light.
- RGB
- rgb(66 135 245)
- HSL
- 217°, 90%, 61%
- OKLCh
- 63.5% 0.179 259.4
Signal Blue in every format
Web & CSSThe everyday formats for stylesheets and design tools.
| Hex | #4287f5 | |
|---|---|---|
| RGB | rgb(66 135 245) | |
| RGB legacy | rgb(66, 135, 245) | |
| RGB percent | rgb(25.88% 52.94% 96.08%) | |
| HSL | hsl(216.9 89.9% 61%) | |
| HSL legacy | hsl(216.9, 89.9%, 61%) | |
| HSV / HSB | hsv(216.9, 73.1%, 96.1%) | |
| HWB | hwb(216.9 25.9% 3.9%) | |
| Nearest name | dodgerblue (approx.) | |
| CMYK | cmyk(73.1%, 44.9%, 0%, 3.9%)Naive conversion. Real print work needs an ICC profile. |
Perceptual & wide gamutModern CSS colour spaces for uniform scales and P3 displays.
| OKLCh | oklch(63.521% 0.17906 259.418)Modern CSS colour space for even palettes — better than HSL when building scales. | |
|---|---|---|
| OKLab | oklab(63.521% -0.03288 -0.17602) | |
| CIE LCh | lch(56.204% 63.033 276.032) | |
| CIE Lab | lab(56.204% 6.623 -62.684) | |
| Display P3 | color(display-p3 0.3279 0.5231 0.9309) | |
| Rec. 2020 | color(rec2020 0.3737 0.4757 0.917) | |
| srgb-linear | color(srgb-linear 0.0545 0.2423 0.9131)Light-linear sRGB — the same numbers a shader wants for maths. | |
| CIE XYZ (D65) | color(xyz-d65 0.2739 0.2508 0.8979) |
ShadersGLSL, HLSL and WGSL vectors in both encoded and linear form.
| GLSL vec3 — sRGB | vec3(0.259, 0.529, 0.961)Encoded values. Use when writing straight to the framebuffer. | |
|---|---|---|
| GLSL vec3 — linear | vec3(0.054, 0.242, 0.913)Light-linear values. Use for lighting, blending and mixing. | |
| GLSL vec4 — sRGB | vec4(0.259, 0.529, 0.961, 1.0) | |
| GLSL vec4 — linear | vec4(0.054, 0.242, 0.913, 1.0) | |
| GLSL ivec3 | ivec3(66, 135, 245) | |
| HLSL float3 — sRGB | float3(0.259, 0.529, 0.961) | |
| HLSL float3 — linear | float3(0.054, 0.242, 0.913) | |
| HLSL float4 — sRGB | float4(0.259, 0.529, 0.961, 1.0) | |
| HLSL half4 — sRGB | half4(0.259, 0.529, 0.961, 1.0) | |
| WGSL vec3f — sRGB | vec3f(0.259, 0.529, 0.961) | |
| WGSL vec4f — sRGB | vec4f(0.259, 0.529, 0.961, 1.0) | |
| WGSL vec3<f32> — linear | vec3<f32>(0.054, 0.242, 0.913) |
Engines & appsConstructors for Unity, Unreal, Godot, Flutter, SwiftUI and Android.
| Unity Color | new Color(0.259f, 0.529f, 0.961f, 1.0f)Color for everyday scripting (0–1). Color32 when you need whole numbers from 0 to 255. | |
|---|---|---|
| Unity Color32 | new Color32(66, 135, 245, 255) | |
| Unreal FLinearColor | FLinearColor(0.0545f, 0.2423f, 0.9131f, 1.0f)FLinearColor for materials and lighting. FColor when you need whole numbers from 0 to 255. | |
| Unreal FColor | FColor(66, 135, 245, 255)Whole numbers from 0 to 255 — use when an API asks for FColor, not FLinearColor. | |
| Godot Color | Color(0.259, 0.529, 0.961, 1) | |
| Flutter Color | Color(0xFF4287F5)Packed ARGB, so alpha comes first. | |
| Android Color | Color.rgb(66, 135, 245) | |
| SwiftUI Color | Color(red: 0.259, green: 0.529, blue: 0.961) | |
| UIKit UIColor | UIColor(red: 0.259, green: 0.529, blue: 0.961, alpha: 1) |
Raw valuesPacked integers and plain arrays.
| 0x hex | 0x4287F5 | |
|---|---|---|
| 0x hex (ARGB) | 0xFF4287F5 | |
| Array 0–1 | [0.259, 0.529, 0.961] | |
| Array 0–255 | [66, 135, 245] | |
| Decimal integer | 4360181 |
Contrast and accessibility
WCAG 2 ratios are what audits and legislation reference. APCA is shown alongside because WCAG 2 is known to misjudge mid-tone backgrounds, and it is the basis of the WCAG 3 draft.
| Pairing | WCAG 2 ratio | Level | APCA | Suitable for |
|---|---|---|---|---|
| Signal Blue on white | 3.49:1 | AA Large | Lc 62 | Headings and large text |
| Signal Blue on black | 6.02:1 | AA | Lc 40 | Non-text elements only |
Signal Blue text on a white background
Signal Blue text on a black background
White text on Signal Blue
Black text on Signal Blue
Tonal scale
Hue held fixed while lightness walks OKLCh, ready to use as a design system ramp.
- 50#ebf9ff
- 100#dcefff
- 200#c0deff
- 300#9bc7ff
- 400#6aa8ff
- 500#4388f6
- 600#2a6dd5
- 700#1655b5
- 800#044198
- 900#00317f
- 950#001756
Tints and shades
Mixed perceptually toward white and black, so the steps feel evenly spaced.
- Tint 1#639cf9
- Tint 2#82b1fc
- Tint 3#a1c5fe
- Tint 4#c0d9ff
- Tint 5#dfecff
- Shade 1#3269c0
- Shade 2#224c8e
- Shade 3#14315f
- Shade 4#071834
- Shade 5#01040e
Colours that work with Signal Blue
Complementary, triadic and analogous partners, rotated in OKLCh so they keep the same apparent brightness.
- #ba7d00
- #e2525d
- #46a329
- #0099d2
- #8b72ee
Closest CSS names
dodgerblueΔEok 0.028cornflowerblueΔEok 0.055royalblueΔEok 0.079mediumslateblueΔEok 0.091steelblueΔEok 0.098mediumpurpleΔEok 0.110