#42B4E5
Closest named color: Deep Sky Blue (#00BFFF). oklch(72.6% 0.123 230.6), rgb(66, 180, 229).
Aa
Black text reads best on this color (8.89:1).
About this color
#42B4E5 is a medium-light, moderately saturated blue. In OKLCH its lightness is 73%, its chroma 0.123 and its hue 231°. 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 8.89:1.
| Hue family | Blues |
| Lightness | medium-light (73%) |
| Chroma | moderately saturated (0.123) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 8.89:1 |
| White text | 2.36:1 |
Values
| HEX | #42B4E5 |
| RGB | rgb(66, 180, 229) |
| HSL | hsl(198, 76%, 58%) |
| OKLCH | oklch(72.6% 0.123 230.6) |
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 #42B4E5 | 2.36:1 | Fails | Lc -51.1 | Large or bold text, headings |
| Black text on #42B4E5 | 8.89:1 | AAA | Lc 57.8 | Large or bold text, headings |
| #42B4E5 text on white | 2.36:1 | Fails | Lc 46.2 | Large or bold text, headings |
| #42B4E5 text on black | 8.89:1 | AAA | Lc -55.8 | 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
#EFF7FB
oklch(97.1% 0.01 228.9)
-
Step 100
100
#DCEDF6
oklch(93.6% 0.022 230.5)
-
Step 200
200
#BEDFF0
oklch(88.5% 0.042 230.2)
-
Step 300
300
#8CCAE9
oklch(80.8% 0.077 230.6)
-
Step 400
400 (this color)
#42B4E5
oklch(72.6% 0.123 230.6)
-
Step 500
500
#0096C7
oklch(63.1% 0.126 230.5)
-
Step 600
600
#007EA8
oklch(55.6% 0.112 230.6)
-
Step 700
700
#006A8E
oklch(49.1% 0.099 230.6)
-
Step 800
800
#005775
oklch(42.8% 0.086 230.3)
-
Step 900
900
#004862
oklch(37.7% 0.076 230.8)
-
Step 950
950
#002B3C
oklch(27.1% 0.054 230.4)
#42B4E5 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) | #9BB2E7 | 0.084 |
| Deuteranopia (no green cones) | #85A2E4 | 0.071 |
| Tritanopia (no blue cones) | #00C1C4 | 0.073 |
| Achromatopsia (no color) | #A9A9A9 | 0.123 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #42B4E5
#42B4E5
oklch(72.6% 0.123 230.6)
- #E48F5C
#E48F5C
oklch(72.8% 0.123 50.8)
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 #42B4E5, 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 0.056
- Vivid Sky Blue #4CC9F0 ΔE 0.059
- Bright Sky Blue #02CCFE ΔE 0.066
- Carolina Blue #8AB8FE ΔE 0.077
- Lightblue #7BC8F6 ΔE 0.078
- Greyblue #77A1B5 ΔE 0.080
- Dark Turquoise #00CED1 ΔE 0.087
Use #42B4E5 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.