#3970CB
Closest named color: Windows Blue (#3778BF). oklch(55.5% 0.153 259.9), rgb(57, 112, 203).
Aa
White text reads best on this color (4.82:1).
About this color
#3970CB is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.153 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.031 away. White text reads best on it, at 4.82:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.153) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.35:1 |
| White text | 4.82:1 |
Values
| HEX | #3970CB |
| RGB | rgb(57, 112, 203) |
| HSL | hsl(217, 58%, 51%) |
| OKLCH | oklch(55.5% 0.153 259.9) |
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 #3970CB | 4.82:1 | AA | Lc -78.5 | Fine for body text |
| Black text on #3970CB | 4.35:1 | AA large text | Lc 31.0 | Non-text elements, placeholder text |
| #3970CB text on white | 4.82:1 | AA | Lc 73.1 | Content text, not long reading |
| #3970CB text on black | 4.35:1 | AA large text | Lc -28.6 | Dividers and decoration only |
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
#F2F6FC
oklch(97.2% 0.009 258.3)
-
Step 100
100
#E2EAF8
oklch(93.5% 0.021 261.8)
-
Step 200
200
#CBDAF3
oklch(88.5% 0.038 260.7)
-
Step 300
300
#A7C2EE
oklch(80.9% 0.069 260.1)
-
Step 400
400
#78A1E5
oklch(70.7% 0.11 260.2)
-
Step 500
500
#5588DE
oklch(63.1% 0.141 260.3)
-
Step 600
600 (this color)
#3970CB
oklch(55.5% 0.153 259.9)
-
Step 700
700
#2C5DB0
oklch(49% 0.143 260.3)
-
Step 800
800
#254D8E
oklch(42.8% 0.117 259.7)
-
Step 900
900
#234072
oklch(37.6% 0.093 260.6)
-
Step 950
950
#152643
oklch(27% 0.059 260.5)
#3970CB 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) | #4279CE | 0.027 |
| Deuteranopia (no green cones) | #256CC9 | 0.020 |
| Tritanopia (no blue cones) | #008593 | 0.121 |
| Achromatopsia (no color) | #727272 | 0.153 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3970CB
#3970CB
oklch(55.5% 0.153 259.9)
- #966A00
#966A00
oklch(55.5% 0.115 79.9)
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 #3970CB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.031
- Royal Blue #4169E1 ΔE 0.041
- Mid Blue #276AB3 ΔE 0.043
- French Blue #436BAD ΔE 0.047
- Flat Blue #3C73A8 ΔE 0.057
- Cerulean Blue #056EEE ΔE 0.058
- Nice Blue #107AB0 ΔE 0.059
- Water Blue #0E87CC ΔE 0.063
Use #3970CB 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.