#637DBF

Closest named color: Cool Blue (#4984B8). oklch(59.8% 0.106 266.9), rgb(99, 125, 191).

Black text reads best on this color (5.21:1).

About this color

#637DBF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 60%, its chroma 0.106 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.036 away. Black text reads best on it, at 5.21:1.

Hue family	Blues
Lightness	medium-dark (60%)
Chroma	moderately saturated (0.106)
Temperature	cool
Nearest name	Cool Blue (#4984B8)
Black text	5.21:1
White text	4.02:1

Values

HEX	#637DBF
RGB	rgb(99, 125, 191)
HSL	hsl(223, 42%, 57%)
OKLCH	oklch(59.8% 0.106 266.9)

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 #637DBF	4.02:1	AA large text	Lc -72.9	Content text, not long reading
Black text on #637DBF	5.21:1	AA	Lc 36.7	Non-text elements, placeholder text
#637DBF text on white	4.02:1	AA large text	Lc 67.4	Content text, not long reading
#637DBF text on black	5.21:1	AA	Lc -34.2	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

#F3F5FA

oklch(97% 0.007 268.5)
Step 100
100

#E5EAF4

oklch(93.6% 0.015 264.5)
Step 200
200

#D0D9ED

oklch(88.5% 0.029 266.4)
Step 300
300

#B1C0E3

oklch(80.8% 0.052 266.9)
Step 400
400

#899FD5

oklch(70.6% 0.083 267.1)
Step 500
500 (this color)

#637DBF

oklch(59.8% 0.106 266.9)
Step 600
600

#5570B7

oklch(55.7% 0.115 266.9)
Step 700
700

#455D9D

oklch(49% 0.107 266.9)
Step 800
800

#394C7F

oklch(42.6% 0.088 267.2)
Step 900
900

#314066

oklch(37.7% 0.068 266.8)
Step 950
950

#1D263C

oklch(27.1% 0.043 266.6)

Export this scale for Tailwind in the Tailwind colors tool

#637DBF 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)	#6483C2	0.016
Deuteranopia (no green cones)	#5B7BBE	0.012
Tritanopia (no blue cones)	#3E8B95	0.095
Achromatopsia (no color)	#7F7F7F	0.106