#337DBF
Closest named color: Windows Blue (#3778BF). oklch(57.5% 0.125 248.8), rgb(51, 125, 191).
Aa
Black text reads best on this color (4.82:1).
About this color
#337DBF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 58%, its chroma 0.125 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.014 away. Black text reads best on it, at 4.82:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | moderately saturated (0.125) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.82:1 |
| White text | 4.35:1 |
Values
| HEX | #337DBF |
| RGB | rgb(51, 125, 191) |
| HSL | hsl(208, 58%, 47%) |
| OKLCH | oklch(57.5% 0.125 248.8) |
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 #337DBF | 4.35:1 | AA large text | Lc -75.3 | Fine for body text |
| Black text on #337DBF | 4.82:1 | AA | Lc 34.3 | Non-text elements, placeholder text |
| #337DBF text on white | 4.35:1 | AA large text | Lc 69.8 | Content text, not long reading |
| #337DBF text on black | 4.82:1 | AA | Lc -31.8 | 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
#E2EBF5
oklch(93.6% 0.017 250.8)
-
Step 200
200
#CADBED
oklch(88.4% 0.031 249.7)
-
Step 300
300
#A5C4E4
oklch(80.8% 0.056 249.4)
-
Step 400
400
#73A5D7
oklch(70.6% 0.091 249.2)
-
Step 500
500
#4C8ECC
oklch(63% 0.116 248.8)
-
Step 600
600 (this color)
#337DBF
oklch(57.5% 0.125 248.8)
-
Step 700
700
#1E649F
oklch(49.1% 0.116 248.6)
-
Step 800
800
#1C5281
oklch(42.8% 0.096 248.6)
-
Step 900
900
#1D4468
oklch(37.7% 0.076 248.9)
-
Step 950
950
#12283D
oklch(27% 0.048 249)
#337DBF 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) | #5F80C2 | 0.045 |
| Deuteranopia (no green cones) | #4B73BE | 0.032 |
| Tritanopia (no blue cones) | #008D95 | 0.093 |
| Achromatopsia (no color) | #797979 | 0.125 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337DBF
#337DBF
oklch(57.5% 0.125 248.8)
- #A86901
#A86901
oklch(57.6% 0.125 69)
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 #337DBF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.014
- Steel Blue #4682B4 ΔE 0.030
- Water Blue #0E87CC ΔE 0.031
- Nice Blue #107AB0 ΔE 0.032
- Cool Blue #4984B8 ΔE 0.032
- Flat Blue #3C73A8 ΔE 0.040
- Blue NCS #118AB2 ΔE 0.048
- Off Blue #5684AE ΔE 0.049
Use #337DBF 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.