#637BE0
Closest named color: Soft Blue (#6488EA). oklch(61.3% 0.155 271.2), rgb(99, 123, 224).
Aa
Black text reads best on this color (5.44:1).
About this color
#637BE0 is a medium-dark, vivid blue. In OKLCH its lightness is 61%, its chroma 0.155 and its hue 271°. Its hue sits on the cool side of the wheel. The nearest named color is Soft Blue (#6488EA), ΔE 0.035 away. Black text reads best on it, at 5.44:1.
| Hue family | Blues |
| Lightness | medium-dark (61%) |
| Chroma | vivid (0.155) |
| Temperature | cool |
| Nearest name | Soft Blue (#6488EA) |
| Black text | 5.44:1 |
| White text | 3.86:1 |
Values
| HEX | #637BE0 |
| RGB | rgb(99, 123, 224) |
| HSL | hsl(228, 67%, 63%) |
| OKLCH | oklch(61.3% 0.155 271.2) |
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 #637BE0 | 3.86:1 | AA large text | Lc -71.4 | Content text, not long reading |
| Black text on #637BE0 | 5.44:1 | AA | Lc 38.2 | Non-text elements, placeholder text |
| #637BE0 text on white | 3.86:1 | AA large text | Lc 65.9 | Content text, not long reading |
| #637BE0 text on black | 5.44:1 | AA | Lc -35.8 | 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
#F3F5FD
oklch(97.1% 0.011 274.9)
-
Step 100
100
#E4E9F9
oklch(93.5% 0.022 272.1)
-
Step 200
200
#CFD8F6
oklch(88.5% 0.042 272.3)
-
Step 300
300
#AEBFF2
oklch(80.9% 0.075 270.3)
-
Step 400
400
#859CEC
oklch(70.8% 0.12 270.9)
-
Step 500
500 (this color)
#637BE0
oklch(61.3% 0.155 271.2)
-
Step 600
600
#5168D4
oklch(55.7% 0.167 271)
-
Step 700
700
#4255B8
oklch(49% 0.157 271.3)
-
Step 800
800
#364695
oklch(42.6% 0.13 271.2)
-
Step 900
900
#2F3C77
oklch(37.8% 0.101 271.4)
-
Step 950
950
#1B2445
oklch(27.1% 0.063 270.3)
#637BE0 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) | #4D87E4 | 0.035 |
| Deuteranopia (no green cones) | #3D7DDE | 0.039 |
| Tritanopia (no blue cones) | #1691A3 | 0.137 |
| Achromatopsia (no color) | #828282 | 0.155 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637BE0
#637BE0
oklch(61.3% 0.155 271.2)
- #A08000
#A08000
oklch(61.3% 0.125 91.1)
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 #637BE0, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Soft Blue #6488EA ΔE 0.035
- Cornflower #6A79F7 ΔE 0.037
- Dark Sky Blue #448EE4 ΔE 0.053
- Medium Slate Blue #7B68EE ΔE 0.059
- Royal Blue #4169E1 ΔE 0.064
- Cornflower Blue #6495ED ΔE 0.068
- Clear Blue #247AFD ΔE 0.068
- Chefchaouen Blue #4895EF ΔE 0.068
Use #637BE0 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.