#21C4E5
Closest named color: Vivid Sky Blue (#4CC9F0). oklch(75.8% 0.13 216.4), rgb(33, 196, 229).
Aa
Black text reads best on this color (10.09:1).
About this color
#21C4E5 is a medium-light, moderately saturated teal or cyan. In OKLCH its lightness is 76%, its chroma 0.130 and its hue 216°. Its hue sits on the cool side of the wheel. The nearest named color is Vivid Sky Blue (#4CC9F0), ΔE 0.029 away. Black text reads best on it, at 10.09:1.
| Hue family | Teals and cyans |
| Lightness | medium-light (76%) |
| Chroma | moderately saturated (0.130) |
| Temperature | cool |
| Nearest name | Vivid Sky Blue (#4CC9F0) |
| Black text | 10.09:1 |
| White text | 2.08:1 |
Values
| HEX | #21C4E5 |
| RGB | rgb(33, 196, 229) |
| HSL | hsl(190, 79%, 51%) |
| OKLCH | oklch(75.8% 0.13 216.4) |
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 #21C4E5 | 2.08:1 | Fails | Lc -44.7 | Non-text elements, placeholder text |
| Black text on #21C4E5 | 10.09:1 | AAA | Lc 63.8 | Content text, not long reading |
| #21C4E5 text on white | 2.08:1 | Fails | Lc 40.1 | Non-text elements, placeholder text |
| #21C4E5 text on black | 10.09:1 | AAA | Lc -62.2 | Content text, not long reading |
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 400.
-
Step 50
50
#EEF7FA
oklch(97% 0.01 219.6)
-
Step 100
100
#D9EEF4
oklch(93.5% 0.024 216.7)
-
Step 200
200
#B9E1EC
oklch(88.5% 0.044 216.3)
-
Step 300
300
#81CEE2
oklch(80.9% 0.081 216.1)
-
Step 400
400 (this color)
#21C4E5
oklch(75.8% 0.13 216.4)
-
Step 500
500
#009AB5
oklch(63.2% 0.112 216)
-
Step 600
600
#008198
oklch(55.6% 0.099 216.1)
-
Step 700
700
#006C80
oklch(49% 0.087 216.4)
-
Step 800
800
#00596A
oklch(42.8% 0.076 216.6)
-
Step 900
900
#004A58
oklch(37.7% 0.067 215.8)
-
Step 950
950
#002C35
oklch(27% 0.048 215.4)
#21C4E5 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) | #AEBEE7 | 0.113 |
| Deuteranopia (no green cones) | #95ACE5 | 0.101 |
| Tritanopia (no blue cones) | #00D0CE | 0.055 |
| Achromatopsia (no color) | #B4B4B4 | 0.130 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #21C4E5
#21C4E5
oklch(75.8% 0.13 216.4)
- #F79175
#F79175
oklch(75.8% 0.13 36.2)
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 #21C4E5, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Vivid Sky Blue #4CC9F0 ΔE 0.029
- Bright Sky Blue #02CCFE ΔE 0.037
- Deep Sky Blue #00BFFF ΔE 0.044
- Dark Turquoise #00CED1 ΔE 0.047
- Aqua Blue #02D8E9 ΔE 0.055
- Medium Turquoise #48D1CC ΔE 0.062
- Lightblue #7BC8F6 ΔE 0.065
- Turquoise Blue #06B1C4 ΔE 0.065
Use #21C4E5 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.