#637FC0
Closest named color: Cool Blue (#4984B8). oklch(60.3% 0.105 265.6), rgb(99, 127, 192).
Aa
Black text reads best on this color (5.32:1).
About this color
#637FC0 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 60%, its chroma 0.105 and its hue 266°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.034 away. Black text reads best on it, at 5.32:1.
| Hue family | Blues |
| Lightness | medium-dark (60%) |
| Chroma | moderately saturated (0.105) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.32:1 |
| White text | 3.94:1 |
Values
| HEX | #637FC0 |
| RGB | rgb(99, 127, 192) |
| HSL | hsl(222, 42%, 57%) |
| OKLCH | oklch(60.3% 0.105 265.6) |
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 #637FC0 | 3.94:1 | AA large text | Lc -72.2 | Content text, not long reading |
| Black text on #637FC0 | 5.32:1 | AA | Lc 37.4 | Non-text elements, placeholder text |
| #637FC0 text on white | 3.94:1 | AA large text | Lc 66.7 | Content text, not long reading |
| #637FC0 text on black | 5.32:1 | AA | Lc -35.0 | 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 500.
-
Step 50
50
#F3F5FA
oklch(97% 0.007 268.5)
-
Step 100
100
#E5EAF4
oklch(93.6% 0.015 264.5)
-
Step 200
200
#D0D9ED
oklch(88.5% 0.029 266.4)
-
Step 300
300
#B1C1E3
oklch(81% 0.051 265.3)
-
Step 400
400
#88A0D4
oklch(70.7% 0.081 265.2)
-
Step 500
500 (this color)
#637FC0
oklch(60.3% 0.105 265.6)
-
Step 600
600
#5370B6
oklch(55.5% 0.114 265.8)
-
Step 700
700
#445E9D
oklch(49.2% 0.106 265.7)
-
Step 800
800
#384D7F
oklch(42.8% 0.087 265.6)
-
Step 900
900
#304066
oklch(37.6% 0.069 265.9)
-
Step 950
950
#1C263C
oklch(27.1% 0.044 265)
#637FC0 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) | #6785C3 | 0.018 |
| Deuteranopia (no green cones) | #5D7CBF | 0.012 |
| Tritanopia (no blue cones) | #3D8D97 | 0.094 |
| Achromatopsia (no color) | #808080 | 0.105 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637FC0
#637FC0
oklch(60.3% 0.105 265.6)
- #9D7C2C
#9D7C2C
oklch(60.3% 0.104 85.8)
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 #637FC0, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.034
- Off Blue #5684AE ΔE 0.038
- Steel Blue #4682B4 ΔE 0.039
- Faded Blue #658CBB ΔE 0.040
- Dusty Blue #5A86AD ΔE 0.041
- Windows Blue #3778BF ΔE 0.052
- Water Blue #0E87CC ΔE 0.060
- Stormy Blue #507B9C ΔE 0.062
Use #637FC0 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.