#3173B7
Closest named color: Windows Blue (#3778BF). oklch(54.7% 0.126 251.8), rgb(49, 115, 183).
Aa
White text reads best on this color (4.92:1).
About this color
#3173B7 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 55%, its chroma 0.126 and its hue 252°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.019 away. White text reads best on it, at 4.92:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | moderately saturated (0.126) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.26:1 |
| White text | 4.92:1 |
Values
| HEX | #3173B7 |
| RGB | rgb(49, 115, 183) |
| HSL | hsl(210, 58%, 45%) |
| OKLCH | oklch(54.7% 0.126 251.8) |
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 #3173B7 | 4.92:1 | AA | Lc -79.2 | Fine for body text |
| Black text on #3173B7 | 4.26:1 | AA large text | Lc 30.3 | Non-text elements, placeholder text |
| #3173B7 text on white | 4.92:1 | AA | Lc 73.8 | Content text, not long reading |
| #3173B7 text on black | 4.26:1 | AA large text | Lc -27.9 | 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
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E2EBF5
oklch(93.6% 0.017 250.8)
-
Step 200
200
#CBDBEE
oklch(88.5% 0.031 252.7)
-
Step 300
300
#A7C4E5
oklch(81% 0.056 251.8)
-
Step 400
400
#76A4D8
oklch(70.6% 0.091 252.1)
-
Step 500
500
#528DCD
oklch(63.1% 0.115 251.8)
-
Step 600
600 (this color)
#3173B7
oklch(54.7% 0.126 251.8)
-
Step 700
700
#2663A0
oklch(49.1% 0.116 251.4)
-
Step 800
800
#215182
oklch(42.7% 0.097 251.5)
-
Step 900
900
#214368
oklch(37.6% 0.075 252.2)
-
Step 950
950
#14283D
oklch(27.1% 0.047 251)
#3173B7 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) | #5477BA | 0.037 |
| Deuteranopia (no green cones) | #406BB6 | 0.024 |
| Tritanopia (no blue cones) | #00838C | 0.095 |
| Achromatopsia (no color) | #707070 | 0.126 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3173B7
#3173B7
oklch(54.7% 0.126 251.8)
- #9A6300
#9A6300
oklch(54.6% 0.117 71.7)
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 #3173B7, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.019
- Flat Blue #3C73A8 ΔE 0.025
- French Blue #436BAD ΔE 0.027
- Mid Blue #276AB3 ΔE 0.028
- Nice Blue #107AB0 ΔE 0.028
- Muted Blue #3B719F ΔE 0.037
- Dull Blue #49759C ΔE 0.048
- Ocean Blue #03719C ΔE 0.050
Use #3173B7 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.