#373EA9
Closest named color: Sapphire (#2138AB). oklch(42.8% 0.169 273.9), rgb(55, 62, 169).
Aa
White text reads best on this color (8.66:1).
About this color
#373EA9 is a dark, vivid blue. In OKLCH its lightness is 43%, its chroma 0.169 and its hue 274°. Its hue sits on the cool side of the wheel. The nearest named color is Sapphire (#2138AB), ΔE 0.032 away. White text reads best on it, at 8.66:1.
| Hue family | Blues |
| Lightness | dark (43%) |
| Chroma | vivid (0.169) |
| Temperature | cool |
| Nearest name | Sapphire (#2138AB) |
| Black text | 2.42:1 |
| White text | 8.66:1 |
Values
| HEX | #373EA9 |
| RGB | rgb(55, 62, 169) |
| HSL | hsl(236, 51%, 44%) |
| OKLCH | oklch(42.8% 0.169 273.9) |
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 #373EA9 | 8.66:1 | AAA | Lc -93.7 | Preferred for body text |
| Black text on #373EA9 | 2.42:1 | Fails | Lc 14.8 | Not readable |
| #373EA9 text on white | 8.66:1 | AAA | Lc 89.2 | Fine for body text |
| #373EA9 text on black | 2.42:1 | Fails | Lc -13.0 | Not readable |
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 800.
-
Step 50
50
#F2F5FF
oklch(97.1% 0.014 272.7)
-
Step 100
100
#E3E9FE
oklch(93.6% 0.029 273.1)
-
Step 200
200
#CDD7FE
oklch(88.4% 0.055 273.9)
-
Step 300
300
#ADBCFF
oklch(80.8% 0.096 274.3)
-
Step 400
400
#8497FF
oklch(70.7% 0.153 274)
-
Step 500
500
#6778FF
oklch(63% 0.199 273.8)
-
Step 600
600
#525CF0
oklch(55.7% 0.219 273.9)
-
Step 700
700
#434AD1
oklch(49.1% 0.204 273.8)
-
Step 800
800 (this color)
#373EA9
oklch(42.8% 0.169 273.9)
-
Step 900
900
#2E3686
oklch(37.6% 0.133 273.8)
-
Step 950
950
#1B214E
oklch(27.1% 0.082 273.9)
#373EA9 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) | #0051AC | 0.054 |
| Deuteranopia (no green cones) | #0046A7 | 0.042 |
| Tritanopia (no blue cones) | #00596D | 0.138 |
| Achromatopsia (no color) | #4B4B4B | 0.169 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #373EA9
#373EA9
oklch(42.8% 0.169 273.9)
- #5F4E00
#5F4E00
oklch(42.9% 0.088 94.5)
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 #373EA9, closest first.
No curated palette has a color within ΔE 0.04 of #373EA9.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Sapphire #2138AB ΔE 0.032
- Blueberry #464196 ΔE 0.039
- Blue Blue #2242C7 ΔE 0.053
- Majorelle Blue #3F37C9 ΔE 0.053
- Dark Slate Blue #483D8B ΔE 0.055
- Cobalt #1E488F ΔE 0.056
- Blue With A Hint Of Purple #533CC6 ΔE 0.062
- Indigo Blue #3A18B1 ΔE 0.064
Use #373EA9 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.