#637FCC
Closest named color: Cool Blue (#4984B8). oklch(60.9% 0.122 267.6), rgb(99, 127, 204).
Aa
Black text reads best on this color (5.43:1).
About this color
#637FCC is a medium-dark, moderately saturated blue. In OKLCH its lightness is 61%, its chroma 0.122 and its hue 268°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.047 away. Black text reads best on it, at 5.43:1.
| Hue family | Blues |
| Lightness | medium-dark (61%) |
| Chroma | moderately saturated (0.122) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.43:1 |
| White text | 3.86:1 |
Values
| HEX | #637FCC |
| RGB | rgb(99, 127, 204) |
| HSL | hsl(224, 51%, 59%) |
| OKLCH | oklch(60.9% 0.122 267.6) |
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 #637FCC | 3.86:1 | AA large text | Lc -71.5 | Content text, not long reading |
| Black text on #637FCC | 5.43:1 | AA | Lc 38.1 | Non-text elements, placeholder text |
| #637FCC text on white | 3.86:1 | AA large text | Lc 66.0 | Content text, not long reading |
| #637FCC text on black | 5.43:1 | AA | Lc -35.7 | 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
#F3F5FB
oklch(97% 0.008 271.3)
-
Step 100
100
#E5EAF6
oklch(93.7% 0.017 267.8)
-
Step 200
200
#CFD9F0
oklch(88.5% 0.033 266.9)
-
Step 300
300
#B0C0E8
oklch(80.9% 0.059 267.9)
-
Step 400
400
#879FDD
oklch(70.8% 0.095 267.7)
-
Step 500
500 (this color)
#637FCC
oklch(60.9% 0.122 267.6)
-
Step 600
600
#516EC0
oklch(55.6% 0.132 267.4)
-
Step 700
700
#425BA6
oklch(49% 0.124 267.8)
-
Step 800
800
#364B86
oklch(42.6% 0.101 267.3)
-
Step 900
900
#2F3F6C
oklch(37.7% 0.08 267.7)
-
Step 950
950
#1C253F
oklch(27% 0.05 268.4)
#637FCC 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) | #6187CF | 0.021 |
| Deuteranopia (no green cones) | #557DCA | 0.018 |
| Tritanopia (no blue cones) | #32909C | 0.110 |
| Achromatopsia (no color) | #828282 | 0.122 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637FCC
#637FCC
oklch(60.9% 0.122 267.6)
- #A27D0C
#A27D0C
oklch(60.9% 0.122 87.2)
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 #637FCC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.047
- Soft Blue #6488EA ΔE 0.048
- Faded Blue #658CBB ΔE 0.050
- Steel Blue #4682B4 ΔE 0.052
- Dark Sky Blue #448EE4 ΔE 0.052
- Off Blue #5684AE ΔE 0.055
- Windows Blue #3778BF ΔE 0.055
- Dusty Blue #5A86AD ΔE 0.058
Use #637FCC 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.