#3F73BB
Closest named color: Windows Blue (#3778BF). oklch(55.4% 0.126 257), rgb(63, 115, 187).
Aa
White text reads best on this color (4.79:1).
About this color
#3F73BB is a medium-dark, moderately saturated blue. In OKLCH its lightness is 55%, its chroma 0.126 and its hue 257°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.014 away. White text reads best on it, at 4.79:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | moderately saturated (0.126) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.38:1 |
| White text | 4.79:1 |
Values
| HEX | #3F73BB |
| RGB | rgb(63, 115, 187) |
| HSL | hsl(215, 50%, 49%) |
| OKLCH | oklch(55.4% 0.126 257) |
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 #3F73BB | 4.79:1 | AA | Lc -78.4 | Fine for body text |
| Black text on #3F73BB | 4.38:1 | AA large text | Lc 31.1 | Non-text elements, placeholder text |
| #3F73BB text on white | 4.79:1 | AA | Lc 73.0 | Content text, not long reading |
| #3F73BB text on black | 4.38:1 | AA large text | Lc -28.7 | 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
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E3EAF5
oklch(93.5% 0.017 259.4)
-
Step 200
200
#CCDAEE
oklch(88.4% 0.031 257.2)
-
Step 300
300
#AAC3E6
oklch(81% 0.057 256.8)
-
Step 400
400
#7CA3D9
oklch(70.8% 0.09 256.6)
-
Step 500
500
#5A8BCF
oklch(63.2% 0.116 256.8)
-
Step 600
600 (this color)
#3F73BB
oklch(55.4% 0.126 257)
-
Step 700
700
#3161A2
oklch(49.2% 0.117 256.7)
-
Step 800
800
#2A4F83
oklch(42.7% 0.097 257.2)
-
Step 900
900
#264269
oklch(37.7% 0.075 256.9)
-
Step 950
950
#17273D
oklch(27% 0.047 256.6)
#3F73BB 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) | #5379BE | 0.029 |
| Deuteranopia (no green cones) | #416DBA | 0.016 |
| Tritanopia (no blue cones) | #00848E | 0.102 |
| Achromatopsia (no color) | #727272 | 0.126 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F73BB
#3F73BB
oklch(55.4% 0.126 257)
- #986800
#986800
oklch(55.4% 0.116 77)
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 #3F73BB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.014
- French Blue #436BAD ΔE 0.028
- Flat Blue #3C73A8 ΔE 0.031
- Mid Blue #276AB3 ΔE 0.036
- Nice Blue #107AB0 ΔE 0.039
- Muted Blue #3B719F ΔE 0.044
- Steel Blue #4682B4 ΔE 0.048
- Dull Blue #49759C ΔE 0.051
Use #3F73BB 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.