#637EB4
Closest named color: Off Blue (#5684AE). oklch(59.5% 0.089 263.6), rgb(99, 126, 180).
Aa
Black text reads best on this color (5.17:1).
About this color
#637EB4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.089 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.025 away. Black text reads best on it, at 5.17:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.089) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.17:1 |
| White text | 4.05:1 |
Values
| HEX | #637EB4 |
| RGB | rgb(99, 126, 180) |
| HSL | hsl(220, 35%, 55%) |
| OKLCH | oklch(59.5% 0.089 263.6) |
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 #637EB4 | 4.05:1 | AA large text | Lc -73.2 | Content text, not long reading |
| Black text on #637EB4 | 5.17:1 | AA | Lc 36.3 | Non-text elements, placeholder text |
| #637EB4 text on white | 4.05:1 | AA large text | Lc 67.7 | Content text, not long reading |
| #637EB4 text on black | 5.17:1 | AA | Lc -33.9 | 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 500.
-
Step 50
50
#F3F5F9
oklch(97% 0.006 264.5)
-
Step 100
100
#E5EAF3
oklch(93.6% 0.013 262.4)
-
Step 200
200
#D1D9EA
oklch(88.4% 0.025 265.6)
-
Step 300
300
#B2C1DE
oklch(80.9% 0.044 263.6)
-
Step 400
400
#8AA1CD
oklch(70.7% 0.07 263.2)
-
Step 500
500 (this color)
#637EB4
oklch(59.5% 0.089 263.6)
-
Step 600
600
#5672AC
oklch(55.6% 0.097 263.9)
-
Step 700
700
#465F94
oklch(49% 0.091 264.2)
-
Step 800
800
#3A4E78
oklch(42.7% 0.075 264.1)
-
Step 900
900
#314161
oklch(37.7% 0.059 263.5)
-
Step 950
950
#1D2639
oklch(27% 0.038 264.5)
#637EB4 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) | #6A82B6 | 0.015 |
| Deuteranopia (no green cones) | #627BB3 | 0.009 |
| Tritanopia (no blue cones) | #458991 | 0.079 |
| Achromatopsia (no color) | #7E7E7E | 0.089 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637EB4
#637EB4
oklch(59.5% 0.089 263.6)
- #987A3C
#987A3C
oklch(59.5% 0.089 83.6)
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 #637EB4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.025
- Dusty Blue #5A86AD ΔE 0.029
- Cool Blue #4984B8 ΔE 0.030
- Steel Blue #4682B4 ΔE 0.032
- Faded Blue #658CBB ΔE 0.039
- Stormy Blue #507B9C ΔE 0.045
- Cerulean #457B9D ΔE 0.052
- Lavender Gray #7E7F9A ΔE 0.053
Use #637EB4 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.