#2178DC
Closest named color: Cerulean Blue (#056EEE). oklch(57.7% 0.172 255.3), rgb(33, 120, 220).
Aa
Black text reads best on this color (4.78:1).
About this color
#2178DC is a medium-dark, vivid blue. In OKLCH its lightness is 58%, its chroma 0.172 and its hue 255°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.041 away. Black text reads best on it, at 4.78:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | vivid (0.172) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.78:1 |
| White text | 4.38:1 |
Values
| HEX | #2178DC |
| RGB | rgb(33, 120, 220) |
| HSL | hsl(212, 74%, 50%) |
| OKLCH | oklch(57.7% 0.172 255.3) |
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 #2178DC | 4.38:1 | AA large text | Lc -75.4 | Fine for body text |
| Black text on #2178DC | 4.78:1 | AA | Lc 34.2 | Non-text elements, placeholder text |
| #2178DC text on white | 4.38:1 | AA large text | Lc 69.9 | Content text, not long reading |
| #2178DC text on black | 4.78:1 | AA | Lc -31.8 | Non-text elements, placeholder text |
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 600.
-
Step 50
50
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#E0EBF9
oklch(93.6% 0.022 254.4)
-
Step 200
200
#C7DBF6
oklch(88.5% 0.043 255.9)
-
Step 300
300
#9FC3F3
oklch(80.8% 0.079 255.7)
-
Step 400
400
#6AA3ED
oklch(70.7% 0.125 255.5)
-
Step 500
500
#3F8AE7
oklch(63.2% 0.159 255.4)
-
Step 600
600 (this color)
#2178DC
oklch(57.7% 0.172 255.3)
-
Step 700
700
#065EB8
oklch(49% 0.16 255.4)
-
Step 800
800
#0D4E95
oklch(42.8% 0.132 255.1)
-
Step 900
900
#154177
oklch(37.7% 0.104 255.6)
-
Step 950
950
#0E2746
oklch(27.1% 0.066 255.2)
#2178DC 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) | #4181E0 | 0.035 |
| Deuteranopia (no green cones) | #0D71DA | 0.021 |
| Tritanopia (no blue cones) | #00909F | 0.130 |
| Achromatopsia (no color) | #787878 | 0.172 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #2178DC
#2178DC
oklch(57.7% 0.172 255.3)
- #A26D00
#A26D00
oklch(57.6% 0.121 75.3)
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 #2178DC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.041
- Royal Blue #4169E1 ΔE 0.042
- Windows Blue #3778BF ΔE 0.046
- Clear Blue #247AFD ΔE 0.050
- Water Blue #0E87CC ΔE 0.051
- Neon Blue #4361EE ΔE 0.066
- Dark Sky Blue #448EE4 ΔE 0.068
- Mid Blue #276AB3 ΔE 0.069
Use #2178DC 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.