#337FB4
Closest named color: Steel Blue (#4682B4). oklch(57.4% 0.11 242.7), rgb(51, 127, 180).
Aa
Black text reads best on this color (4.83:1).
About this color
#337FB4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 57%, its chroma 0.110 and its hue 243°. Its hue sits on the cool side of the wheel. The nearest named color is Steel Blue (#4682B4), ΔE 0.019 away. Black text reads best on it, at 4.83:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | moderately saturated (0.110) |
| Temperature | cool |
| Nearest name | Steel Blue (#4682B4) |
| Black text | 4.83:1 |
| White text | 4.34:1 |
Values
| HEX | #337FB4 |
| RGB | rgb(51, 127, 180) |
| HSL | hsl(205, 56%, 45%) |
| OKLCH | oklch(57.4% 0.11 242.7) |
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 #337FB4 | 4.34:1 | AA large text | Lc -75.3 | Fine for body text |
| Black text on #337FB4 | 4.83:1 | AA | Lc 34.3 | Non-text elements, placeholder text |
| #337FB4 text on white | 4.34:1 | AA large text | Lc 69.8 | Content text, not long reading |
| #337FB4 text on black | 4.83:1 | AA | Lc -31.9 | 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 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
#CADCEA
oklch(88.5% 0.027 241.2)
-
Step 300
300
#A6C5DF
oklch(80.9% 0.05 243.7)
-
Step 400
400
#74A7CE
oklch(70.7% 0.079 242.1)
-
Step 500
500
#4D90C2
oklch(63% 0.102 242.9)
-
Step 600
600 (this color)
#337FB4
oklch(57.4% 0.11 242.7)
-
Step 700
700
#1F6696
oklch(49.1% 0.103 243.1)
-
Step 800
800
#1C5479
oklch(42.8% 0.084 241.8)
-
Step 900
900
#1E4562
oklch(37.6% 0.067 243.4)
-
Step 950
950
#132939
oklch(27.1% 0.041 242)
#337FB4 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) | #6780B6 | 0.053 |
| Deuteranopia (no green cones) | #5574B3 | 0.040 |
| Tritanopia (no blue cones) | #008C92 | 0.077 |
| Achromatopsia (no color) | #797979 | 0.110 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337FB4
#337FB4
oklch(57.4% 0.11 242.7)
- #A66829
#A66829
oklch(57.4% 0.11 62.4)
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 #337FB4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Steel Blue #4682B4 ΔE 0.019
- Nice Blue #107AB0 ΔE 0.025
- Cool Blue #4984B8 ΔE 0.025
- Windows Blue #3778BF ΔE 0.029
- Blue NCS #118AB2 ΔE 0.034
- Flat Blue #3C73A8 ΔE 0.035
- Cerulean #457B9D ΔE 0.036
- Off Blue #5684AE ΔE 0.038
Use #337FB4 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.