Colour reference

Indigo 500

#6366f1

RGB: rgb(99 102 241)
HSL: 239°, 84%, 67%
OKLCh: 58.5% 0.204 277.1

Indigo 500 in every format

Web & CSSThe everyday formats for stylesheets and design tools.

Hex	`#6366f1`
RGB	`rgb(99 102 241)`
RGB legacy	`rgb(99, 102, 241)`
RGB percent	`rgb(38.82% 40% 94.51%)`
HSL	`hsl(238.7 83.5% 66.7%)`
HSL legacy	`hsl(238.7, 83.5%, 66.7%)`
HSV / HSB	`hsv(238.7, 58.9%, 94.5%)`
HWB	`hwb(238.7 38.8% 5.5%)`
Nearest name	`mediumslateblue (approx.)`
CMYK	`cmyk(58.9%, 57.7%, 0%, 5.5%)`Naive conversion. Real print work needs an ICC profile.

Perceptual & wide gamutModern CSS colour spaces for uniform scales and P3 displays.

OKLCh	`oklch(58.54% 0.20406 277.117)`Modern CSS colour space for even palettes — better than HSL when building scales.
OKLab	`oklab(58.54% 0.02528 -0.20248)`
CIE LCh	`lch(49.049% 78.017 292.889)`
CIE Lab	`lab(49.049% 30.345 -71.874)`
Display P3	`color(display-p3 0.3904 0.3996 0.9126)`
Rec. 2020	`color(rec2020 0.3828 0.3557 0.8958)`
srgb-linear	`color(srgb-linear 0.1248 0.1329 0.8796)`Light-linear sRGB — the same numbers a shader wants for maths.
CIE XYZ (D65)	`color(xyz-d65 0.2577 0.1851 0.8544)`

ShadersGLSL, HLSL and WGSL vectors in both encoded and linear form.

GLSL vec3 — sRGB	`vec3(0.388, 0.4, 0.945)`Encoded values. Use when writing straight to the framebuffer.
GLSL vec3 — linear	`vec3(0.125, 0.133, 0.88)`Light-linear values. Use for lighting, blending and mixing.
GLSL vec4 — sRGB	`vec4(0.388, 0.4, 0.945, 1.0)`
GLSL vec4 — linear	`vec4(0.125, 0.133, 0.88, 1.0)`
GLSL ivec3	`ivec3(99, 102, 241)`
HLSL float3 — sRGB	`float3(0.388, 0.4, 0.945)`
HLSL float3 — linear	`float3(0.125, 0.133, 0.88)`
HLSL float4 — sRGB	`float4(0.388, 0.4, 0.945, 1.0)`
HLSL half4 — sRGB	`half4(0.388, 0.4, 0.945, 1.0)`
WGSL vec3f — sRGB	`vec3f(0.388, 0.4, 0.945)`
WGSL vec4f — sRGB	`vec4f(0.388, 0.4, 0.945, 1.0)`
WGSL vec3<f32> — linear	`vec3<f32>(0.125, 0.133, 0.88)`

Engines & appsConstructors for Unity, Unreal, Godot, Flutter, SwiftUI and Android.

Unity Color	`new Color(0.388f, 0.4f, 0.945f, 1.0f)`Color for everyday scripting (0–1). Color32 when you need whole numbers from 0 to 255.
Unity Color32	`new Color32(99, 102, 241, 255)`
Unreal FLinearColor	`FLinearColor(0.1248f, 0.1329f, 0.8796f, 1.0f)`FLinearColor for materials and lighting. FColor when you need whole numbers from 0 to 255.
Unreal FColor	`FColor(99, 102, 241, 255)`Whole numbers from 0 to 255 — use when an API asks for FColor, not FLinearColor.
Godot Color	`Color(0.388, 0.4, 0.945, 1)`
Flutter Color	`Color(0xFF6366F1)`Packed ARGB, so alpha comes first.
Android Color	`Color.rgb(99, 102, 241)`
SwiftUI Color	`Color(red: 0.388, green: 0.4, blue: 0.945)`
UIKit UIColor	`UIColor(red: 0.388, green: 0.4, blue: 0.945, alpha: 1)`

Raw valuesPacked integers and plain arrays.

0x hex	`0x6366F1`
0x hex (ARGB)	`0xFF6366F1`
Array 0–1	`[0.388, 0.4, 0.945]`
Array 0–255	`[99, 102, 241]`
Decimal integer	`6514417`

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
Indigo 500 on white	4.47:1	AA Large	Lc 71	Headings and large text
Indigo 500 on black	4.70:1	AA	Lc 31	Non-text elements only

Indigo 500 text on a white background

Indigo 500 text on a black background

White text on Indigo 500

Black text on Indigo 500

Tonal scale

Hue held fixed while lightness walks OKLCh, ready to use as a design system ramp.

50#f2f6ff
100#e5ebff
200#d0d9ff
300#b4bfff
400#919dff
500#7177ff
600#5a5ce1
700#4745c0
800#3731a2
900#2a2288
950#17075d

Tints and shades

Mixed perceptually toward white and black, so the steps feel evenly spaced.

Tint 1#7982f6
Tint 2#919cfa
Tint 3#abb6fd
Tint 4#c6ceff
Tint 5#e2e7ff
Shade 1#4c4ebd
Shade 2#36388c
Shade 3#21235d
Shade 4#0f0f33
Shade 5#02020d

Colours that work with Indigo 500

Complementary, triadic and analogous partners, rotated in OKLCh so they keep the same apparent brightness.

#937a00
#d93a00
#009752
#007fe3
#9c4fd8

Closest CSS names

mediumslateblueΔEok 0.036
royalblueΔEok 0.047
slateblueΔEok 0.060
mediumpurpleΔEok 0.087
dodgerblueΔEok 0.106
bluevioletΔEok 0.118