#42B5EA
Closest named color: Deep Sky Blue (#00BFFF). oklch(73.1% 0.127 232.5), rgb(66, 181, 234).
Aa
Black text reads best on this color (9.02:1).
About this color
#42B5EA is a medium-light, moderately saturated blue. In OKLCH its lightness is 73%, its chroma 0.127 and its hue 232°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.036 away. Black text reads best on it, at 9.02:1.
| Hue family | Blues |
| Lightness | medium-light (73%) |
| Chroma | moderately saturated (0.127) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 9.02:1 |
| White text | 2.32:1 |
Values
| HEX | #42B5EA |
| RGB | rgb(66, 181, 234) |
| HSL | hsl(199, 80%, 59%) |
| OKLCH | oklch(73.1% 0.127 232.5) |
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 #42B5EA | 2.32:1 | Fails | Lc -50.4 | Large or bold text, headings |
| Black text on #42B5EA | 9.02:1 | AAA | Lc 58.5 | Large or bold text, headings |
| #42B5EA text on white | 2.32:1 | Fails | Lc 45.5 | Large or bold text, headings |
| #42B5EA text on black | 9.02:1 | AAA | Lc -56.6 | 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
#DCEDF7
oklch(93.6% 0.023 233.4)
-
Step 200
200
#BDDFF2
oklch(88.5% 0.044 232.4)
-
Step 300
300
#8CCAEC
oklch(80.9% 0.08 233.1)
-
Step 400
400 (this color)
#42B5EA
oklch(73.1% 0.127 232.5)
-
Step 500
500
#0095CA
oklch(63% 0.13 232.7)
-
Step 600
600
#007EAA
oklch(55.7% 0.113 231.8)
-
Step 700
700
#006990
oklch(49% 0.101 232.9)
-
Step 800
800
#005677
oklch(42.6% 0.088 233.1)
-
Step 900
900
#004863
oklch(37.7% 0.077 231.8)
-
Step 950
950
#002B3D
oklch(27.1% 0.055 231.9)
#42B5EA 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) | #9BB3ED | 0.083 |
| Deuteranopia (no green cones) | #84A3E9 | 0.070 |
| Tritanopia (no blue cones) | #00C3C7 | 0.077 |
| Achromatopsia (no color) | #AAAAAA | 0.127 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #42B5EA
#42B5EA
oklch(73.1% 0.127 232.5)
- #E69058
#E69058
oklch(73.1% 0.127 52.6)
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 #42B5EA, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.036
- Vivid Sky Blue #4CC9F0 ΔE 0.056
- Bright Sky Blue #02CCFE ΔE 0.061
- Turquoise Blue #06B1C4 ΔE 0.063
- Carolina Blue #8AB8FE ΔE 0.072
- Lightblue #7BC8F6 ΔE 0.074
- Sky #82CAFC ΔE 0.085
- Greyblue #77A1B5 ΔE 0.086
Use #42B5EA 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.