#1B73CC
Closest named color: Windows Blue (#3778BF). oklch(55.4% 0.159 253.4), rgb(27, 115, 204).
Aa
White text reads best on this color (4.80:1).
About this color
#1B73CC is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.159 and its hue 253°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.032 away. White text reads best on it, at 4.80:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.159) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.37:1 |
| White text | 4.80:1 |
Values
| HEX | #1B73CC |
| RGB | rgb(27, 115, 204) |
| HSL | hsl(210, 77%, 45%) |
| OKLCH | oklch(55.4% 0.159 253.4) |
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 #1B73CC | 4.80:1 | AA | Lc -78.2 | Fine for body text |
| Black text on #1B73CC | 4.37:1 | AA large text | Lc 31.3 | Non-text elements, placeholder text |
| #1B73CC text on white | 4.80:1 | AA | Lc 72.8 | Content text, not long reading |
| #1B73CC text on black | 4.37:1 | AA large text | Lc -28.9 | Dividers and decoration only |
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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E1EBF8
oklch(93.6% 0.021 254.9)
-
Step 200
200
#C7DBF3
oklch(88.4% 0.04 253)
-
Step 300
300
#A1C4EE
oklch(80.9% 0.071 253.2)
-
Step 400
400
#6CA4E6
oklch(70.7% 0.114 253.3)
-
Step 500
500
#418BDF
oklch(63% 0.147 253.6)
-
Step 600
600 (this color)
#1B73CC
oklch(55.4% 0.159 253.4)
-
Step 700
700
#0B60B1
oklch(49% 0.148 253.6)
-
Step 800
800
#104F8F
oklch(42.7% 0.122 253.4)
-
Step 900
900
#164272
oklch(37.6% 0.095 253.4)
-
Step 950
950
#0F2743
oklch(27% 0.06 253.9)
#1B73CC 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) | #447ACF | 0.037 |
| Deuteranopia (no green cones) | #1F6BCA | 0.021 |
| Tritanopia (no blue cones) | #008895 | 0.118 |
| Achromatopsia (no color) | #727272 | 0.159 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #1B73CC
#1B73CC
oklch(55.4% 0.159 253.4)
- #9B6600
#9B6600
oklch(55.3% 0.118 73.6)
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 #1B73CC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.032
- Mid Blue #276AB3 ΔE 0.042
- Royal Blue #4169E1 ΔE 0.049
- Nice Blue #107AB0 ΔE 0.052
- French Blue #436BAD ΔE 0.053
- Cerulean Blue #056EEE ΔE 0.055
- Water Blue #0E87CC ΔE 0.055
- Flat Blue #3C73A8 ΔE 0.059
Use #1B73CC 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.