#637591
Closest named color: Grey Blue (#647D8E). oklch(55.8% 0.049 259.1), rgb(99, 117, 145).
Aa
White text reads best on this color (4.68:1).
About this color
#637591 is a medium-dark, muted blue. In OKLCH its lightness is 56%, its chroma 0.049 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Grey Blue (#647D8E), ΔE 0.026 away. White text reads best on it, at 4.68:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | muted (0.049) |
| Temperature | cool |
| Nearest name | Grey Blue (#647D8E) |
| Black text | 4.48:1 |
| White text | 4.68:1 |
Values
| HEX | #637591 |
| RGB | rgb(99, 117, 145) |
| HSL | hsl(217, 19%, 48%) |
| OKLCH | oklch(55.8% 0.049 259.1) |
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 #637591 | 4.68:1 | AA | Lc -78.0 | Fine for body text |
| Black text on #637591 | 4.48:1 | AA large text | Lc 31.6 | Non-text elements, placeholder text |
| #637591 text on white | 4.68:1 | AA | Lc 72.5 | Content text, not long reading |
| #637591 text on black | 4.48:1 | AA large text | Lc -29.2 | Dividers and decoration only |
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
#F4F5F7
oklch(97% 0.003 264.5)
-
Step 100
100
#E7EAEE
oklch(93.6% 0.006 255.5)
-
Step 200
200
#D4D9E1
oklch(88.4% 0.012 259.8)
-
Step 300
300
#B8C1CF
oklch(80.8% 0.022 259.2)
-
Step 400
400
#94A2B7
oklch(70.8% 0.035 258.4)
-
Step 500
500
#798BA5
oklch(63.2% 0.045 257.5)
-
Step 600
600 (this color)
#637591
oklch(55.8% 0.049 259.1)
-
Step 700
700
#51627B
oklch(49.2% 0.045 257.9)
-
Step 800
800
#435064
oklch(42.8% 0.037 258.9)
-
Step 900
900
#384251
oklch(37.6% 0.029 258.4)
-
Step 950
950
#212730
oklch(27.1% 0.019 258.4)
#637591 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) | #6B7692 | 0.012 |
| Deuteranopia (no green cones) | #677290 | 0.009 |
| Tritanopia (no blue cones) | #567B7E | 0.044 |
| Achromatopsia (no color) | #747474 | 0.049 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637591
#637591
oklch(55.8% 0.049 259.1)
- #847153
#847153
oklch(55.9% 0.05 78.8)
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 #637591, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Grey Blue #647D8E ΔE 0.026
- Metallic Blue #4F738E ΔE 0.027
- Stormy Blue #507B9C ΔE 0.028
- Battleship Gray #6C757D ΔE 0.033
- Battleship Grey #6B7C85 ΔE 0.034
- Dull Blue #49759C ΔE 0.034
- Cerulean #457B9D ΔE 0.037
- Slate Gray #708090 ΔE 0.039
Use #637591 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.