#51A8FF
Closest named color: Cornflower Blue (#6495ED). oklch(71.7% 0.153 250.8), rgb(81, 168, 255).
Aa
Black text reads best on this color (8.39:1).
About this color
#51A8FF is a medium-light, vivid blue. In OKLCH its lightness is 72%, its chroma 0.153 and its hue 251°. Its hue sits on the cool side of the wheel. The nearest named color is Cornflower Blue (#6495ED), ΔE 0.051 away. Black text reads best on it, at 8.39:1.
| Hue family | Blues |
| Lightness | medium-light (72%) |
| Chroma | vivid (0.153) |
| Temperature | cool |
| Nearest name | Cornflower Blue (#6495ED) |
| Black text | 8.39:1 |
| White text | 2.50:1 |
Values
| HEX | #51A8FF |
| RGB | rgb(81, 168, 255) |
| HSL | hsl(210, 100%, 66%) |
| OKLCH | oklch(71.7% 0.153 250.8) |
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 #51A8FF | 2.50:1 | Fails | Lc -53.9 | Large or bold text, headings |
| Black text on #51A8FF | 8.39:1 | AAA | Lc 55.2 | Large or bold text, headings |
| #51A8FF text on white | 2.50:1 | Fails | Lc 48.8 | Large or bold text, headings |
| #51A8FF text on black | 8.39:1 | AAA | Lc -53.2 | 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
#EFF6FE
oklch(97% 0.013 251.6)
-
Step 100
100
#DDECFC
oklch(93.7% 0.027 249.9)
-
Step 200
200
#C0DCFC
oklch(88.4% 0.053 251.9)
-
Step 300
300
#92C5FD
oklch(80.8% 0.096 251.3)
-
Step 400
400 (this color)
#51A8FF
oklch(71.7% 0.153 250.8)
-
Step 500
500
#008BF2
oklch(63% 0.183 250.9)
-
Step 600
600
#0075CD
oklch(55.6% 0.161 250.9)
-
Step 700
700
#0062AD
oklch(49.1% 0.142 250.8)
-
Step 800
800
#00508F
oklch(42.6% 0.123 250.8)
-
Step 900
900
#004379
oklch(37.8% 0.109 250.7)
-
Step 950
950
#00274B
oklch(27% 0.079 251.1)
#51A8FF 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) | #81ADFF | 0.049 |
| Deuteranopia (no green cones) | #689CFD | 0.034 |
| Tritanopia (no blue cones) | #00BCC8 | 0.115 |
| Achromatopsia (no color) | #A4A4A4 | 0.153 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #51A8FF
#51A8FF
oklch(71.7% 0.153 250.8)
- #DE900B
#DE900B
oklch(71.6% 0.152 70.7)
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 #51A8FF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cornflower Blue #6495ED ΔE 0.051
- Chefchaouen Blue #4895EF ΔE 0.054
- Deep Sky Blue #00BFFF ΔE 0.064
- Periwinkle Blue #8F99FB ΔE 0.069
- Carolina Blue #8AB8FE ΔE 0.075
- Dodger Blue #1E90FF ΔE 0.075
- Dark Sky Blue #448EE4 ΔE 0.077
- Soft Blue #6488EA ΔE 0.083
Use #51A8FF 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.