#637E8D
Closest named color: Grey Blue (#647D8E). oklch(57.7% 0.039 232.6), rgb(99, 126, 141).
Aa
Black text reads best on this color (4.89:1).
About this color
#637E8D is a medium-dark, muted blue. In OKLCH its lightness is 58%, its chroma 0.039 and its hue 233°. Its hue sits on the cool side of the wheel. The nearest named color is Grey Blue (#647D8E), ΔE 0.004 away. Black text reads best on it, at 4.89:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | muted (0.039) |
| Temperature | cool |
| Nearest name | Grey Blue (#647D8E) |
| Black text | 4.89:1 |
| White text | 4.28:1 |
Values
| HEX | #637E8D |
| RGB | rgb(99, 126, 141) |
| HSL | hsl(201, 18%, 47%) |
| OKLCH | oklch(57.7% 0.039 232.6) |
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 #637E8D | 4.28:1 | AA large text | Lc -75.1 | Fine for body text |
| Black text on #637E8D | 4.89:1 | AA | Lc 34.5 | Non-text elements, placeholder text |
| #637E8D text on white | 4.28:1 | AA large text | Lc 69.6 | Content text, not long reading |
| #637E8D text on black | 4.89:1 | AA | Lc -32.0 | 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
#F4F6F7
oklch(97.2% 0.003 228.8)
-
Step 100
100
#E7EAED
oklch(93.6% 0.005 247.9)
-
Step 200
200
#D3DADE
oklch(88.4% 0.009 232.4)
-
Step 300
300
#B6C3CA
oklch(80.9% 0.017 231)
-
Step 400
400
#90A4AF
oklch(70.7% 0.028 231.8)
-
Step 500
500
#758E9C
oklch(63.2% 0.035 232.6)
-
Step 600
600 (this color)
#637E8D
oklch(57.7% 0.039 232.6)
-
Step 700
700
#4C6572
oklch(49.2% 0.036 231)
-
Step 800
800
#3F525D
oklch(42.7% 0.03 233.8)
-
Step 900
900
#35444C
oklch(37.7% 0.024 231.5)
-
Step 950
950
#1F282D
oklch(27% 0.016 232.4)
#637E8D 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) | #777D8E | 0.027 |
| Deuteranopia (no green cones) | #71788D | 0.024 |
| Tritanopia (no blue cones) | #568283 | 0.028 |
| Achromatopsia (no color) | #7A7A7A | 0.039 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637E8D
#637E8D
oklch(57.7% 0.039 232.6)
- #8D7465
#8D7465
oklch(57.9% 0.039 52.7)
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 #637E8D, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Grey Blue #647D8E ΔE 0.004
- Battleship Grey #6B7C85 ΔE 0.015
- Slate Gray #708090 ΔE 0.019
- Steel Grey #6F828A ΔE 0.022
- Battleship Gray #6C757D ΔE 0.030
- Steel #738595 ΔE 0.032
- Stormy Blue #507B9C ΔE 0.035
- Medium Grey #7D7F7C ΔE 0.043
Use #637E8D 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.