#51B5FA
Closest named color: Deep Sky Blue (#00BFFF). oklch(74.3% 0.136 242), rgb(81, 181, 250).
Aa
Black text reads best on this color (9.33:1).
About this color
#51B5FA is a medium-light, moderately saturated blue. In OKLCH its lightness is 74%, its chroma 0.136 and its hue 242°. Its hue sits on the cool side of the wheel. The nearest named color is Deep Sky Blue (#00BFFF), ΔE 0.034 away. Black text reads best on it, at 9.33:1.
| Hue family | Blues |
| Lightness | medium-light (74%) |
| Chroma | moderately saturated (0.136) |
| Temperature | cool |
| Nearest name | Deep Sky Blue (#00BFFF) |
| Black text | 9.33:1 |
| White text | 2.24:1 |
Values
| HEX | #51B5FA |
| RGB | rgb(81, 181, 250) |
| HSL | hsl(204, 94%, 65%) |
| OKLCH | oklch(74.3% 0.136 242) |
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 #51B5FA | 2.24:1 | Fails | Lc -48.8 | Large or bold text, headings |
| Black text on #51B5FA | 9.33:1 | AAA | Lc 60.0 | Large or bold text, headings |
| #51B5FA text on white | 2.24:1 | Fails | Lc 44.0 | Non-text elements, placeholder text |
| #51B5FA text on black | 9.33:1 | AAA | Lc -58.1 | 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
#EFF7FD
oklch(97.2% 0.012 239.9)
-
Step 100
100
#DCECF9
oklch(93.5% 0.025 242.3)
-
Step 200
200
#BFDEF6
oklch(88.6% 0.047 241.4)
-
Step 300
300
#8FC8F3
oklch(80.9% 0.085 241.6)
-
Step 400
400 (this color)
#51B5FA
oklch(74.3% 0.136 242)
-
Step 500
500
#0092DB
oklch(63.2% 0.149 241.7)
-
Step 600
600
#007AB9
oklch(55.5% 0.132 242.1)
-
Step 700
700
#00679C
oklch(49.2% 0.116 241.5)
-
Step 800
800
#005481
oklch(42.7% 0.101 241.9)
-
Step 900
900
#00466D
oklch(37.8% 0.09 242.2)
-
Step 950
950
#002943
oklch(27% 0.065 242.6)
#51B5FA 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) | #96B6FD | 0.068 |
| Deuteranopia (no green cones) | #7EA6F9 | 0.052 |
| Tritanopia (no blue cones) | #00C6CD | 0.097 |
| Achromatopsia (no color) | #ADADAD | 0.136 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51B5FA
#51B5FA
oklch(74.3% 0.136 242)
- #E89646
#E89646
oklch(74.2% 0.136 62.1)
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 #51B5FA, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Deep Sky Blue #00BFFF ΔE 0.034
- Carolina Blue #8AB8FE ΔE 0.055
- Vivid Sky Blue #4CC9F0 ΔE 0.061
- Bright Sky Blue #02CCFE ΔE 0.062
- Lightblue #7BC8F6 ΔE 0.069
- Sky #82CAFC ΔE 0.076
- Cornflower Blue #6495ED ΔE 0.083
- Chefchaouen Blue #4895EF ΔE 0.087
Use #51B5FA 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.