#21B0EF
Closest named color: Deep Sky Blue (#00BFFF). oklch(71.5% 0.144 234.6), rgb(33, 176, 239).
Aa
Black text reads best on this color (8.52:1).
About this color
#21B0EF is a medium-light, vivid blue. In OKLCH its lightness is 72%, its chroma 0.144 and its hue 235°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.042 away. Black text reads best on it, at 8.52:1.
| Hue family | Blues |
| Lightness | medium-light (72%) |
| Chroma | vivid (0.144) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 8.52:1 |
| White text | 2.46:1 |
Values
| HEX | #21B0EF |
| RGB | rgb(33, 176, 239) |
| HSL | hsl(198, 87%, 53%) |
| OKLCH | oklch(71.5% 0.144 234.6) |
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 #21B0EF | 2.46:1 | Fails | Lc -52.9 | Large or bold text, headings |
| Black text on #21B0EF | 8.52:1 | AAA | Lc 56.1 | Large or bold text, headings |
| #21B0EF text on white | 2.46:1 | Fails | Lc 47.9 | Large or bold text, headings |
| #21B0EF text on black | 8.52:1 | AAA | Lc -54.1 | Large or bold text, headings |
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
#EEF7FC
oklch(97.1% 0.012 231.7)
-
Step 100
100
#DAEDF9
oklch(93.6% 0.026 235.4)
-
Step 200
200
#BADFF6
oklch(88.4% 0.05 235.4)
-
Step 300
300
#85CBF2
oklch(81% 0.089 233.8)
-
Step 400
400 (this color)
#21B0EF
oklch(71.5% 0.144 234.6)
-
Step 500
500
#0095CD
oklch(63.1% 0.132 234.2)
-
Step 600
600
#007DAD
oklch(55.6% 0.117 234.3)
-
Step 700
700
#006992
oklch(49.1% 0.103 234.3)
-
Step 800
800
#005679
oklch(42.8% 0.09 234.7)
-
Step 900
900
#004765
oklch(37.6% 0.08 234.9)
-
Step 950
950
#002A3E
oklch(26.9% 0.057 235.2)
#21B0EF 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) | #91AFF2 | 0.088 |
| Deuteranopia (no green cones) | #769DEE | 0.072 |
| Tritanopia (no blue cones) | #00C1C6 | 0.088 |
| Achromatopsia (no color) | #A5A5A5 | 0.144 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #21B0EF
#21B0EF
oklch(71.5% 0.144 234.6)
- #E78841
#E78841
oklch(71.6% 0.144 54.5)
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 #21B0EF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.042
- Turquoise Blue #06B1C4 ΔE 0.067
- Chefchaouen Blue #4895EF ΔE 0.073
- Bright Sky Blue #02CCFE ΔE 0.075
- Vivid Sky Blue #4CC9F0 ΔE 0.076
- Cornflower Blue #6495ED ΔE 0.078
- Carolina Blue #8AB8FE ΔE 0.087
- Dark Sky Blue #448EE4 ΔE 0.090
Use #21B0EF 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.