#637FEF
Closest named color: Cornflower (#6A79F7). oklch(63% 0.17 270.3), rgb(99, 127, 239).
Aa
Black text reads best on this color (5.81:1).
About this color
#637FEF is a medium-light, vivid blue. In OKLCH its lightness is 63%, its chroma 0.170 and its hue 270°. Its hue sits on the cool side of the wheel. The nearest named color is Cornflower (#6A79F7), ΔE 0.021 away. Black text reads best on it, at 5.81:1.
| Hue family | Blues |
| Lightness | medium-light (63%) |
| Chroma | vivid (0.170) |
| Temperature | cool |
| Nearest name | Cornflower (#6A79F7) |
| Black text | 5.81:1 |
| White text | 3.61:1 |
Values
| HEX | #637FEF |
| RGB | rgb(99, 127, 239) |
| HSL | hsl(228, 81%, 66%) |
| OKLCH | oklch(63% 0.17 270.3) |
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 #637FEF | 3.61:1 | AA large text | Lc -69.0 | Content text, not long reading |
| Black text on #637FEF | 5.81:1 | AA | Lc 40.6 | Non-text elements, placeholder text |
| #637FEF text on white | 3.61:1 | AA large text | Lc 63.5 | Content text, not long reading |
| #637FEF text on black | 5.81:1 | AA | Lc -38.2 | 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
#F2F5FD
oklch(97% 0.011 269.6)
-
Step 100
100
#E3E9FB
oklch(93.5% 0.025 271.1)
-
Step 200
200
#CDD8F9
oklch(88.4% 0.047 270.8)
-
Step 300
300
#ACBEF7
oklch(80.8% 0.083 270.9)
-
Step 400
400
#819BF4
oklch(70.7% 0.134 270.4)
-
Step 500
500 (this color)
#637FEF
oklch(63% 0.17 270.3)
-
Step 600
600
#4C65DE
oklch(55.5% 0.186 270.4)
-
Step 700
700
#3E53C0
oklch(49% 0.172 270.5)
-
Step 800
800
#33459C
oklch(42.8% 0.143 270.4)
-
Step 900
900
#2C3B7C
oklch(37.7% 0.111 270.5)
-
Step 950
950
#1A2348
oklch(27% 0.07 270.8)
#637FEF 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) | #488DF3 | 0.040 |
| Deuteranopia (no green cones) | #3281ED | 0.044 |
| Tritanopia (no blue cones) | #0098AB | 0.150 |
| Achromatopsia (no color) | #878787 | 0.170 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #637FEF
#637FEF
oklch(63% 0.17 270.3)
- #A78500
#A78500
oklch(63.1% 0.129 90.6)
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 #637FEF, closest first.
No curated palette has a color within ΔE 0.04 of #637FEF.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cornflower #6A79F7 ΔE 0.021
- Soft Blue #6488EA ΔE 0.026
- Dark Sky Blue #448EE4 ΔE 0.051
- Cornflower Blue #6495ED ΔE 0.058
- Chefchaouen Blue #4895EF ΔE 0.059
- Medium Slate Blue #7B68EE ΔE 0.059
- Clear Blue #247AFD ΔE 0.060
- Lavender Blue #8B88F8 ΔE 0.061
Use #637FEF 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.