#21B5E3
Closest named color: Deep Sky Blue (#00BFFF). oklch(72.1% 0.131 225.6), rgb(33, 181, 227).
Aa
Black text reads best on this color (8.78:1).
About this color
#21B5E3 is a medium-light, moderately saturated teal or cyan. In OKLCH its lightness is 72%, its chroma 0.131 and its hue 226°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.043 away. Black text reads best on it, at 8.78:1.
| Hue family | Teals and cyans |
| Lightness | medium-light (72%) |
| Chroma | moderately saturated (0.131) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 8.78:1 |
| White text | 2.39:1 |
Values
| HEX | #21B5E3 |
| RGB | rgb(33, 181, 227) |
| HSL | hsl(194, 78%, 51%) |
| OKLCH | oklch(72.1% 0.131 225.6) |
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 #21B5E3 | 2.39:1 | Fails | Lc -51.5 | Large or bold text, headings |
| Black text on #21B5E3 | 8.78:1 | AAA | Lc 57.4 | Large or bold text, headings |
| #21B5E3 text on white | 2.39:1 | Fails | Lc 46.6 | Large or bold text, headings |
| #21B5E3 text on black | 8.78:1 | AAA | Lc -55.5 | 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
#EEF7FB
oklch(97.1% 0.011 226)
-
Step 100
100
#DAEEF6
oklch(93.7% 0.024 223.7)
-
Step 200
200
#BAE0F0
oklch(88.5% 0.046 225.3)
-
Step 300
300
#85CCE9
oklch(80.9% 0.082 225.8)
-
Step 400
400 (this color)
#21B5E3
oklch(72.1% 0.131 225.6)
-
Step 500
500
#0097C0
oklch(63% 0.12 225.7)
-
Step 600
600
#007FA2
oklch(55.5% 0.106 225.7)
-
Step 700
700
#006B89
oklch(49.1% 0.094 225.7)
-
Step 800
800
#005871
oklch(42.8% 0.081 225.4)
-
Step 900
900
#00495E
oklch(37.7% 0.071 225)
-
Step 950
950
#002B39
oklch(26.9% 0.051 225.5)
#21B5E3 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) | #9CB1E5 | 0.099 |
| Deuteranopia (no green cones) | #83A0E2 | 0.085 |
| Tritanopia (no blue cones) | #00C2C4 | 0.068 |
| Achromatopsia (no color) | #A8A8A8 | 0.132 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #21B5E3
#21B5E3
oklch(72.1% 0.131 225.6)
- #E8895B
#E8895B
oklch(72.2% 0.131 45.9)
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 #21B5E3, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.043
- Turquoise Blue #06B1C4 ΔE 0.047
- Vivid Sky Blue #4CC9F0 ΔE 0.062
- Bright Sky Blue #02CCFE ΔE 0.066
- Dark Turquoise #00CED1 ΔE 0.083
- Light Sea Green #20B2AA ΔE 0.084
- Greyblue #77A1B5 ΔE 0.085
- Topaz #13BBAF ΔE 0.085
Use #21B5E3 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.