#637EA8
Closest named color: Off Blue (#5684AE). oklch(58.9% 0.072 259.1), rgb(99, 126, 168).
Aa
Black text reads best on this color (5.08:1).
About this color
#637EA8 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.072 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.021 away. Black text reads best on it, at 5.08:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.072) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.08:1 |
| White text | 4.13:1 |
Values
| HEX | #637EA8 |
| RGB | rgb(99, 126, 168) |
| HSL | hsl(217, 28%, 52%) |
| OKLCH | oklch(58.9% 0.072 259.1) |
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 #637EA8 | 4.13:1 | AA large text | Lc -73.9 | Content text, not long reading |
| Black text on #637EA8 | 5.08:1 | AA | Lc 35.7 | Non-text elements, placeholder text |
| #637EA8 text on white | 4.13:1 | AA large text | Lc 68.4 | Content text, not long reading |
| #637EA8 text on black | 5.08:1 | AA | Lc -33.3 | 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
#F4F5F8
oklch(97% 0.004 271.4)
-
Step 100
100
#E6EAF0
oklch(93.6% 0.009 258.3)
-
Step 200
200
#D2DAE5
oklch(88.6% 0.017 256.3)
-
Step 300
300
#B4C2D6
oklch(81% 0.032 257.2)
-
Step 400
400
#8DA2C1
oklch(70.7% 0.051 258)
-
Step 500
500
#718BB2
oklch(63.2% 0.066 258.3)
-
Step 600
600 (this color)
#637EA8
oklch(58.9% 0.072 259.1)
-
Step 700
700
#496187
oklch(49% 0.068 259.4)
-
Step 800
800
#3C506D
oklch(42.7% 0.055 257.6)
-
Step 900
900
#344259
oklch(37.7% 0.044 260.2)
-
Step 950
950
#1E2734
oklch(27% 0.028 257.5)
#637EA8 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) | #6F80AA | 0.018 |
| Deuteranopia (no green cones) | #677AA7 | 0.012 |
| Tritanopia (no blue cones) | #4B878C | 0.064 |
| Achromatopsia (no color) | #7D7D7D | 0.072 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637EA8
#637EA8
oklch(58.9% 0.072 259.1)
- #94784A
#94784A
oklch(58.9% 0.072 79.1)
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 #637EA8, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.021
- Dusty Blue #5A86AD ΔE 0.023
- Stormy Blue #507B9C ΔE 0.032
- Steel Blue #4682B4 ΔE 0.034
- Cool Blue #4984B8 ΔE 0.035
- Grey Blue #647D8E ΔE 0.040
- Cerulean #457B9D ΔE 0.040
- Lavender Gray #7E7F9A ΔE 0.042
Use #637EA8 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.