#637CBC
Closest named color: Cool Blue (#4984B8). oklch(59.4% 0.103 267.1), rgb(99, 124, 188).
Aa
Black text reads best on this color (5.13:1).
About this color
#637CBC is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.103 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.035 away. Black text reads best on it, at 5.13:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.103) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.13:1 |
| White text | 4.08:1 |
Values
| HEX | #637CBC |
| RGB | rgb(99, 124, 188) |
| HSL | hsl(223, 40%, 56%) |
| OKLCH | oklch(59.4% 0.103 267.1) |
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 #637CBC | 4.08:1 | AA large text | Lc -73.4 | Content text, not long reading |
| Black text on #637CBC | 5.13:1 | AA | Lc 36.1 | Non-text elements, placeholder text |
| #637CBC text on white | 4.08:1 | AA large text | Lc 67.9 | Content text, not long reading |
| #637CBC text on black | 5.13:1 | AA | Lc -33.7 | 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
#D1D9EC
oklch(88.5% 0.028 267.5)
-
Step 300
300
#B2C0E2
oklch(80.8% 0.051 267.6)
-
Step 400
400
#8A9FD3
oklch(70.6% 0.08 267.3)
-
Step 500
500 (this color)
#637CBC
oklch(59.4% 0.103 267.1)
-
Step 600
600
#5670B5
oklch(55.7% 0.112 267.1)
-
Step 700
700
#465D9B
oklch(49% 0.104 267.2)
-
Step 800
800
#3A4C7E
oklch(42.6% 0.086 267.7)
-
Step 900
900
#324065
oklch(37.7% 0.066 267.4)
-
Step 950
950
#1D263B
oklch(27.1% 0.041 266)
#637CBC 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) | #6482BF | 0.017 |
| Deuteranopia (no green cones) | #5B7ABB | 0.012 |
| Tritanopia (no blue cones) | #408993 | 0.092 |
| Achromatopsia (no color) | #7E7E7E | 0.103 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637CBC
#637CBC
oklch(59.4% 0.103 267.1)
- #997A2B
#997A2B
oklch(59.4% 0.103 86.9)
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 #637CBC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.035
- Off Blue #5684AE ΔE 0.038
- Steel Blue #4682B4 ΔE 0.038
- Dusty Blue #5A86AD ΔE 0.042
- Faded Blue #658CBB ΔE 0.046
- Windows Blue #3778BF ΔE 0.049
- Stormy Blue #507B9C ΔE 0.057
- Flat Blue #3C73A8 ΔE 0.061
Use #637CBC 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.