#637EA3
Closest named color: Off Blue (#5684AE). oklch(58.7% 0.065 256.4), rgb(99, 126, 163).
Aa
Black text reads best on this color (5.04:1).
About this color
#637EA3 is a medium-dark, muted blue. In OKLCH its lightness is 59%, its chroma 0.065 and its hue 256°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.023 away. Black text reads best on it, at 5.04:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | muted (0.065) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.04:1 |
| White text | 4.16:1 |
Values
| HEX | #637EA3 |
| RGB | rgb(99, 126, 163) |
| HSL | hsl(215, 26%, 51%) |
| OKLCH | oklch(58.7% 0.065 256.4) |
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 #637EA3 | 4.16:1 | AA large text | Lc -74.1 | Content text, not long reading |
| Black text on #637EA3 | 5.04:1 | AA | Lc 35.4 | Non-text elements, placeholder text |
| #637EA3 text on white | 4.16:1 | AA large text | Lc 68.6 | Content text, not long reading |
| #637EA3 text on black | 5.04:1 | AA | Lc -33.0 | 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
#F4F6F8
oklch(97.2% 0.003 247.9)
-
Step 100
100
#E6EAF0
oklch(93.6% 0.009 258.3)
-
Step 200
200
#D2DAE4
oklch(88.5% 0.016 253.9)
-
Step 300
300
#B5C2D4
oklch(81% 0.029 256.5)
-
Step 400
400
#8EA2BE
oklch(70.6% 0.047 256.8)
-
Step 500
500
#728BAE
oklch(63% 0.06 256.8)
-
Step 600
600 (this color)
#637EA3
oklch(58.7% 0.065 256.4)
-
Step 700
700
#4A6283
oklch(49.1% 0.061 256.5)
-
Step 800
800
#3D506A
oklch(42.7% 0.05 256.4)
-
Step 900
900
#344356
oklch(37.8% 0.038 254.6)
-
Step 950
950
#1F2733
oklch(27.1% 0.025 258.3)
#637EA3 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) | #7080A5 | 0.019 |
| Deuteranopia (no green cones) | #6979A2 | 0.015 |
| Tritanopia (no blue cones) | #4D868A | 0.058 |
| Achromatopsia (no color) | #7C7C7C | 0.065 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637EA3
#637EA3
oklch(58.7% 0.065 256.4)
- #93774F
#93774F
oklch(58.6% 0.066 75.8)
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 #637EA3, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.023
- Dusty Blue #5A86AD ΔE 0.024
- Stormy Blue #507B9C ΔE 0.028
- Grey Blue #647D8E ΔE 0.032
- Slate Gray #708090 ΔE 0.035
- Steel Blue #4682B4 ΔE 0.037
- Cerulean #457B9D ΔE 0.038
- Lavender Gray #7E7F9A ΔE 0.039
Use #637EA3 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.