#637DB0
Closest named color: Off Blue (#5684AE). oklch(59.1% 0.084 263.3), rgb(99, 125, 176).
Aa
Black text reads best on this color (5.09:1).
About this color
#637DB0 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.084 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.024 away. Black text reads best on it, at 5.09:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.084) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.09:1 |
| White text | 4.12:1 |
Values
| HEX | #637DB0 |
| RGB | rgb(99, 125, 176) |
| HSL | hsl(220, 33%, 54%) |
| OKLCH | oklch(59.1% 0.084 263.3) |
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 #637DB0 | 4.12:1 | AA large text | Lc -73.8 | Content text, not long reading |
| Black text on #637DB0 | 5.09:1 | AA | Lc 35.8 | Non-text elements, placeholder text |
| #637DB0 text on white | 4.12:1 | AA large text | Lc 68.3 | Content text, not long reading |
| #637DB0 text on black | 5.09:1 | AA | Lc -33.4 | 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
#E6EAF1
oklch(93.6% 0.01 261.8)
-
Step 200
200
#D2D9E8
oklch(88.4% 0.022 265.8)
-
Step 300
300
#B4C1DA
oklch(80.9% 0.038 263.6)
-
Step 400
400
#8DA1C7
oklch(70.7% 0.06 263.1)
-
Step 500
500
#7189B9
oklch(63% 0.078 263.8)
-
Step 600
600 (this color)
#637DB0
oklch(59.1% 0.084 263.3)
-
Step 700
700
#49608D
oklch(49.1% 0.078 263.1)
-
Step 800
800
#3C4F73
oklch(42.8% 0.065 262.6)
-
Step 900
900
#33415D
oklch(37.6% 0.052 263.7)
-
Step 950
950
#1E2636
oklch(26.9% 0.032 263.8)
#637DB0 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) | #6B81B2 | 0.016 |
| Deuteranopia (no green cones) | #627AAF | 0.009 |
| Tritanopia (no blue cones) | #47888F | 0.076 |
| Achromatopsia (no color) | #7D7D7D | 0.084 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637DB0
#637DB0
oklch(59.1% 0.084 263.3)
- #96793F
#96793F
oklch(59.1% 0.084 83.1)
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 #637DB0, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.024
- Dusty Blue #5A86AD ΔE 0.028
- Cool Blue #4984B8 ΔE 0.031
- Steel Blue #4682B4 ΔE 0.032
- Stormy Blue #507B9C ΔE 0.040
- Faded Blue #658CBB ΔE 0.042
- Cerulean #457B9D ΔE 0.047
- Dull Blue #49759C ΔE 0.050
Use #637DB0 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.