#637BC3
Closest named color: Cool Blue (#4984B8). oklch(59.6% 0.114 268.8), rgb(99, 123, 195).
Aa
Black text reads best on this color (5.15:1).
About this color
#637BC3 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 60%, its chroma 0.114 and its hue 269°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.043 away. Black text reads best on it, at 5.15:1.
| Hue family | Blues |
| Lightness | medium-dark (60%) |
| Chroma | moderately saturated (0.114) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.15:1 |
| White text | 4.07:1 |
Values
| HEX | #637BC3 |
| RGB | rgb(99, 123, 195) |
| HSL | hsl(225, 44%, 58%) |
| OKLCH | oklch(59.6% 0.114 268.8) |
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 #637BC3 | 4.07:1 | AA large text | Lc -73.3 | Content text, not long reading |
| Black text on #637BC3 | 5.15:1 | AA | Lc 36.2 | Non-text elements, placeholder text |
| #637BC3 text on white | 4.07:1 | AA large text | Lc 67.8 | Content text, not long reading |
| #637BC3 text on black | 5.15:1 | AA | Lc -33.8 | 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
#F3F5FB
oklch(97% 0.008 271.3)
-
Step 100
100
#E5EAF5
oklch(93.6% 0.016 266.3)
-
Step 200
200
#D0D9EE
oklch(88.5% 0.031 267.2)
-
Step 300
300
#B2C0E6
oklch(81% 0.056 269.2)
-
Step 400
400
#8A9FD9
oklch(70.8% 0.089 268.8)
-
Step 500
500 (this color)
#637BC3
oklch(59.6% 0.114 268.8)
-
Step 600
600
#556EBC
oklch(55.6% 0.125 268.7)
-
Step 700
700
#465CA2
oklch(49.2% 0.115 268.8)
-
Step 800
800
#394B83
oklch(42.6% 0.096 268.7)
-
Step 900
900
#313F69
oklch(37.7% 0.074 268.7)
-
Step 950
950
#1D253E
oklch(27% 0.048 269.5)
#637BC3 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) | #5F82C6 | 0.019 |
| Deuteranopia (no green cones) | #557AC1 | 0.018 |
| Tritanopia (no blue cones) | #3B8A96 | 0.101 |
| Achromatopsia (no color) | #7E7E7E | 0.114 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637BC3
#637BC3
oklch(59.6% 0.114 268.8)
- #9B7B19
#9B7B19
oklch(59.7% 0.114 88.9)
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 #637BC3, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.043
- Steel Blue #4682B4 ΔE 0.046
- Windows Blue #3778BF ΔE 0.048
- Off Blue #5684AE ΔE 0.048
- Faded Blue #658CBB ΔE 0.052
- Dusty Blue #5A86AD ΔE 0.053
- Water Blue #0E87CC ΔE 0.063
- Soft Blue #6488EA ΔE 0.063
Use #637BC3 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.