#21397E
Closest named color: Twilight Blue (#0A437A). oklch(36.8% 0.121 266.1), rgb(33, 57, 126).
Aa
White text reads best on this color (10.76:1).
About this color
#21397E is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.121 and its hue 266°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.032 away. White text reads best on it, at 10.76:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.121) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.95:1 |
| White text | 10.76:1 |
Values
| HEX | #21397E |
| RGB | rgb(33, 57, 126) |
| HSL | hsl(225, 58%, 31%) |
| OKLCH | oklch(36.8% 0.121 266.1) |
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 #21397E | 10.76:1 | AAA | Lc -98.5 | Preferred for body text |
| Black text on #21397E | 1.95:1 | Fails | Lc 9.3 | Not readable |
| #21397E text on white | 10.76:1 | AAA | Lc 94.6 | Preferred for body text |
| #21397E text on black | 1.95:1 | Fails | Lc -8.0 | Not readable |
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 900.
-
Step 50
50
#F2F5FE
oklch(97% 0.012 271.3)
-
Step 100
100
#E2EAFC
oklch(93.6% 0.026 266.6)
-
Step 200
200
#CAD9FB
oklch(88.5% 0.05 266.5)
-
Step 300
300
#A5C0FC
oklch(80.9% 0.09 265.7)
-
Step 400
400
#769CFB
oklch(70.7% 0.146 266.3)
-
Step 500
500
#5480F8
oklch(63% 0.186 266.1)
-
Step 600
600
#3C66E7
oklch(55.6% 0.201 266.2)
-
Step 700
700
#2E54C9
oklch(49.2% 0.187 265.9)
-
Step 800
800
#2745A2
oklch(42.6% 0.155 266.3)
-
Step 900
900 (this color)
#21397E
oklch(36.8% 0.121 266.1)
-
Step 950
950
#15234B
oklch(26.9% 0.076 266.7)
#21397E 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) | #094280 | 0.027 |
| Deuteranopia (no green cones) | #003A7D | 0.023 |
| Tritanopia (no blue cones) | #004A55 | 0.099 |
| Achromatopsia (no color) | #3E3E3E | 0.121 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #21397E
#21397E
oklch(36.8% 0.121 266.1)
- #513C00
#513C00
oklch(36.9% 0.076 86.3)
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 #21397E, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.032
- Marine Blue #01386A ΔE 0.044
- Cobalt #1E488F ΔE 0.048
- Dark Slate Blue #483D8B ΔE 0.063
- Light Navy #155084 ΔE 0.065
- Marine #042E60 ΔE 0.068
- Prussian Blue #1D3557 ΔE 0.068
- Blueberry #464196 ΔE 0.071
Use #21397E 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.