#637D97
Closest named color: Grey Blue (#647D8E). oklch(57.9% 0.05 248.7), rgb(99, 125, 151).
Aa
Black text reads best on this color (4.91:1).
About this color
#637D97 is a medium-dark, muted blue. In OKLCH its lightness is 58%, its chroma 0.050 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Grey Blue (#647D8E), ΔE 0.014 away. Black text reads best on it, at 4.91:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | muted (0.050) |
| Temperature | cool |
| Nearest name | Grey Blue (#647D8E) |
| Black text | 4.91:1 |
| White text | 4.27:1 |
Values
| HEX | #637D97 |
| RGB | rgb(99, 125, 151) |
| HSL | hsl(210, 21%, 49%) |
| OKLCH | oklch(57.9% 0.05 248.7) |
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 #637D97 | 4.27:1 | AA large text | Lc -75.0 | Fine for body text |
| Black text on #637D97 | 4.91:1 | AA | Lc 34.5 | Non-text elements, placeholder text |
| #637D97 text on white | 4.27:1 | AA large text | Lc 69.5 | Content text, not long reading |
| #637D97 text on black | 4.91:1 | AA | Lc -32.1 | 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
#E7EAEE
oklch(93.6% 0.006 255.5)
-
Step 200
200
#D3DAE1
oklch(88.5% 0.012 248)
-
Step 300
300
#B6C2CF
oklch(80.9% 0.023 250.3)
-
Step 400
400
#90A3B7
oklch(70.7% 0.036 249.7)
-
Step 500
500
#748CA5
oklch(63% 0.047 249.6)
-
Step 600
600 (this color)
#637D97
oklch(57.9% 0.05 248.7)
-
Step 700
700
#4C637A
oklch(49% 0.046 248.8)
-
Step 800
800
#3E5164
oklch(42.7% 0.04 248.8)
-
Step 900
900
#354351
oklch(37.6% 0.03 248.6)
-
Step 950
950
#1F2730
oklch(26.9% 0.02 251.6)
#637D97 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) | #737D98 | 0.022 |
| Deuteranopia (no green cones) | #6D7896 | 0.018 |
| Tritanopia (no blue cones) | #538385 | 0.043 |
| Achromatopsia (no color) | #7A7A7A | 0.050 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637D97
#637D97
oklch(57.9% 0.05 248.7)
- #8E755A
#8E755A
oklch(57.9% 0.05 68.7)
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 #637D97, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Grey Blue #647D8E ΔE 0.014
- Slate Gray #708090 ΔE 0.023
- Stormy Blue #507B9C ΔE 0.025
- Battleship Grey #6B7C85 ΔE 0.028
- Steel Grey #6F828A ΔE 0.033
- Steel #738595 ΔE 0.034
- Cerulean #457B9D ΔE 0.036
- Dusty Blue #5A86AD ΔE 0.036
Use #637D97 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.