#637FAF
Closest named color: Off Blue (#5684AE). oklch(59.4% 0.081 260.9), rgb(99, 127, 175).
Aa
Black text reads best on this color (5.18:1).
About this color
#637FAF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.081 and its hue 261°. Its hue sits on the cool side of the wheel. The nearest named color is Off Blue (#5684AE), ΔE 0.020 away. Black text reads best on it, at 5.18:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.081) |
| Temperature | cool |
| Nearest name | Off Blue (#5684AE) |
| Black text | 5.18:1 |
| White text | 4.04:1 |
Values
| HEX | #637FAF |
| RGB | rgb(99, 127, 175) |
| HSL | hsl(218, 32%, 54%) |
| OKLCH | oklch(59.4% 0.081 260.9) |
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 #637FAF | 4.04:1 | AA large text | Lc -73.2 | Content text, not long reading |
| Black text on #637FAF | 5.18:1 | AA | Lc 36.4 | Non-text elements, placeholder text |
| #637FAF text on white | 4.04:1 | AA large text | Lc 67.7 | Content text, not long reading |
| #637FAF text on black | 5.18:1 | AA | Lc -34.0 | 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 500.
-
Step 50
50
#F3F5F9
oklch(97% 0.006 264.5)
-
Step 100
100
#E6EAF2
oklch(93.6% 0.012 264.5)
-
Step 200
200
#D1DAE8
oklch(88.6% 0.022 259.2)
-
Step 300
300
#B2C1DB
oklch(80.8% 0.04 261.5)
-
Step 400
400
#8AA2C9
oklch(70.8% 0.063 260)
-
Step 500
500 (this color)
#637FAF
oklch(59.4% 0.081 260.9)
-
Step 600
600
#5673A7
oklch(55.6% 0.088 261.6)
-
Step 700
700
#46618F
oklch(49.2% 0.081 260.7)
-
Step 800
800
#3A4F74
oklch(42.7% 0.067 261.3)
-
Step 900
900
#31425E
oklch(37.7% 0.053 260.1)
-
Step 950
950
#1D2737
oklch(27.1% 0.033 259.6)
#637FAF 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) | #6E82B1 | 0.017 |
| Deuteranopia (no green cones) | #657BAE | 0.011 |
| Tritanopia (no blue cones) | #478990 | 0.071 |
| Achromatopsia (no color) | #7E7E7E | 0.081 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637FAF
#637FAF
oklch(59.4% 0.081 260.9)
- #977944
#977944
oklch(59.3% 0.08 80.5)
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 #637FAF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Off Blue #5684AE ΔE 0.020
- Dusty Blue #5A86AD ΔE 0.023
- Cool Blue #4984B8 ΔE 0.030
- Steel Blue #4682B4 ΔE 0.031
- Faded Blue #658CBB ΔE 0.037
- Stormy Blue #507B9C ΔE 0.039
- Cerulean #457B9D ΔE 0.047
- Lavender Gray #7E7F9A ΔE 0.047
Use #637FAF 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.