#043F99
Closest named color: Cobalt (#1E488F). oklch(39.6% 0.158 260.1), rgb(4, 63, 153).
Aa
White text reads best on this color (9.65:1).
About this color
#043F99 is a dark, vivid blue. In OKLCH its lightness is 40%, its chroma 0.158 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.036 away. White text reads best on it, at 9.65:1.
| Hue family | Blues |
| Lightness | dark (40%) |
| Chroma | vivid (0.158) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.17:1 |
| White text | 9.65:1 |
Values
| HEX | #043F99 |
| RGB | rgb(4, 63, 153) |
| HSL | hsl(216, 95%, 31%) |
| OKLCH | oklch(39.6% 0.158 260.1) |
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 #043F99 | 9.65:1 | AAA | Lc -95.9 | Preferred for body text |
| Black text on #043F99 | 2.17:1 | Fails | Lc 12.4 | Not readable |
| #043F99 text on white | 9.65:1 | AAA | Lc 91.6 | Preferred for body text |
| #043F99 text on black | 2.17:1 | Fails | Lc -10.8 | 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 900.
-
Step 50
50
#F0F6FF
oklch(97.1% 0.014 258.3)
-
Step 100
100
#DEEBFF
oklch(93.6% 0.031 258.9)
-
Step 200
200
#C4DAFF
oklch(88.4% 0.057 260.8)
-
Step 300
300
#9DC2FF
oklch(81% 0.096 260.2)
-
Step 400
400
#669FFF
oklch(70.7% 0.154 260.3)
-
Step 500
500
#3983FF
oklch(63.1% 0.199 260.2)
-
Step 600
600
#0066F5
oklch(55.5% 0.229 260.2)
-
Step 700
700
#0056D0
oklch(49.2% 0.201 260.1)
-
Step 800
800
#0046AC
oklch(42.7% 0.175 260)
-
Step 900
900 (this color)
#043F99
oklch(39.6% 0.158 260.1)
-
Step 950
950
#042356
oklch(27.1% 0.1 259.9)
#043F99 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) | #004B9C | 0.032 |
| Deuteranopia (no green cones) | #003E97 | 0.005 |
| Tritanopia (no blue cones) | #005665 | 0.120 |
| Achromatopsia (no color) | #454545 | 0.158 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #043F99
#043F99
oklch(39.6% 0.158 260.1)
- #5D4100
#5D4100
oklch(39.6% 0.082 80.8)
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 #043F99, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.036
- Sapphire #2138AB ΔE 0.037
- Twilight Blue #0A437A ΔE 0.054
- Light Navy #155084 ΔE 0.064
- Blueberry #464196 ΔE 0.067
- Dusk Blue #26538D ΔE 0.068
- Dark Slate Blue #483D8B ΔE 0.073
- Deep Sea Blue #015482 ΔE 0.075
Use #043F99 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.