#637DB2
Closest named color: Off Blue (#5684AE). oklch(59.1% 0.087 263.9), rgb(99, 125, 178).
Aa
Black text reads best on this color (5.10:1).
About this color
#637DB2 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.087 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.026 away. Black text reads best on it, at 5.10:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.087) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.10:1 |
| White text | 4.11:1 |
Values
| HEX | #637DB2 |
| RGB | rgb(99, 125, 178) |
| HSL | hsl(220, 34%, 54%) |
| OKLCH | oklch(59.1% 0.087 263.9) |
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 #637DB2 | 4.11:1 | AA large text | Lc -73.7 | Content text, not long reading |
| Black text on #637DB2 | 5.10:1 | AA | Lc 35.9 | Non-text elements, placeholder text |
| #637DB2 text on white | 4.11:1 | AA large text | Lc 68.2 | Content text, not long reading |
| #637DB2 text on black | 5.10:1 | AA | Lc -33.5 | 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 600.
-
Step 50
50
#F4F5F9
oklch(97.1% 0.005 275)
-
Step 100
100
#E6EAF2
oklch(93.6% 0.012 264.5)
-
Step 200
200
#D2D9E8
oklch(88.4% 0.022 265.8)
-
Step 300
300
#B4C1DB
oklch(80.9% 0.039 264.3)
-
Step 400
400
#8DA1C9
oklch(70.8% 0.063 264)
-
Step 500
500
#7189BB
oklch(63.1% 0.081 264.4)
-
Step 600
600 (this color)
#637DB2
oklch(59.1% 0.087 263.9)
-
Step 700
700
#49608F
oklch(49.2% 0.081 263.8)
-
Step 800
800
#3C4E74
oklch(42.6% 0.068 264.4)
-
Step 900
900
#33415E
oklch(37.6% 0.053 264.2)
-
Step 950
950
#1E2637
oklch(26.9% 0.034 264.8)
#637DB2 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) | #6A81B4 | 0.015 |
| Deuteranopia (no green cones) | #627AB1 | 0.009 |
| Tritanopia (no blue cones) | #468890 | 0.077 |
| Achromatopsia (no color) | #7D7D7D | 0.087 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637DB2
#637DB2
oklch(59.1% 0.087 263.9)
- #96793C
#96793C
oklch(59.1% 0.087 84.1)
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 #637DB2, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.026
- Dusty Blue #5A86AD ΔE 0.030
- Cool Blue #4984B8 ΔE 0.031
- Steel Blue #4682B4 ΔE 0.032
- Faded Blue #658CBB ΔE 0.042
- Stormy Blue #507B9C ΔE 0.043
- Cerulean #457B9D ΔE 0.050
- Dull Blue #49759C ΔE 0.052
Use #637DB2 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.