#337BB4
Closest named color: Nice Blue (#107AB0). oklch(56.4% 0.114 245.8), rgb(51, 123, 180).
Aa
Black text reads best on this color (4.63:1).
About this color
#337BB4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 56%, its chroma 0.114 and its hue 246°. Its hue sits on the cool side of the wheel. The nearest named color is Nice Blue (#107AB0), ΔE 0.020 away. Black text reads best on it, at 4.63:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | moderately saturated (0.114) |
| Temperature | cool |
| Nearest name | Nice Blue (#107AB0) |
| Black text | 4.63:1 |
| White text | 4.53:1 |
Values
| HEX | #337BB4 |
| RGB | rgb(51, 123, 180) |
| HSL | hsl(207, 56%, 45%) |
| OKLCH | oklch(56.4% 0.114 245.8) |
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 #337BB4 | 4.53:1 | AA | Lc -76.7 | Fine for body text |
| Black text on #337BB4 | 4.63:1 | AA | Lc 32.9 | Non-text elements, placeholder text |
| #337BB4 text on white | 4.53:1 | AA | Lc 71.2 | Content text, not long reading |
| #337BB4 text on black | 4.63:1 | AA | Lc -30.5 | 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
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E2EBF3
oklch(93.6% 0.015 244.7)
-
Step 200
200
#CADCEB
oklch(88.6% 0.028 243.1)
-
Step 300
300
#A6C5E0
oklch(81% 0.051 244.8)
-
Step 400
400
#75A6D1
oklch(70.7% 0.082 245.8)
-
Step 500
500
#4F8FC5
oklch(63% 0.105 246)
-
Step 600
600 (this color)
#337BB4
oklch(56.4% 0.114 245.8)
-
Step 700
700
#226599
oklch(49.1% 0.106 246.1)
-
Step 800
800
#1F537C
oklch(42.8% 0.087 245.8)
-
Step 900
900
#1F4563
oklch(37.8% 0.067 244.8)
-
Step 950
950
#13283A
oklch(26.9% 0.043 246.2)
#337BB4 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) | #617DB6 | 0.047 |
| Deuteranopia (no green cones) | #4F71B3 | 0.035 |
| Tritanopia (no blue cones) | #00898F | 0.083 |
| Achromatopsia (no color) | #767676 | 0.114 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337BB4
#337BB4
oklch(56.4% 0.114 245.8)
- #A2661D
#A2661D
oklch(56.4% 0.114 65.9)
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 #337BB4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Nice Blue #107AB0 ΔE 0.020
- Windows Blue #3778BF ΔE 0.021
- Flat Blue #3C73A8 ΔE 0.026
- Steel Blue #4682B4 ΔE 0.028
- Cool Blue #4984B8 ΔE 0.034
- Cerulean #457B9D ΔE 0.038
- Muted Blue #3B719F ΔE 0.038
- Dull Blue #49759C ΔE 0.039
Use #337BB4 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.