Onyx #343A40
Onyx is a dark close to neutral grey with hex code #343A40 and RGB rgb(52, 58, 64).
Aa
White text reads best on this color (11.50:1).
About this color
#343A40 is a dark close to neutral grey. In OKLCH its lightness is 35%, its chroma 0.013. It has too little chroma to lean warm or cool. It is the named color Onyx. White text reads best on it, at 11.50:1.
| Hue family | Neutrals |
| Lightness | dark (35%) |
| Chroma | close to neutral grey (0.013) |
| Temperature | neutral |
| Nearest name | Onyx |
| Black text | 1.82:1 |
| White text | 11.50:1 |
Colors that go with Onyx
Matches found by rotating Onyx around the OKLCH hue wheel, each labelled with the closest name in our list.
Onyx is close to neutral, so it has no hue to rotate. It pairs with almost any color; try the palettes below.
Color palettes with Onyx
Curated color palettes that contain a color within ΔE 0.06 (OKLab) of Onyx, closest first.
Similar named colors
The eight named colors closest to Onyx, with their ΔE distance.
- Charcoal Grey #3C4142 ΔE 0.027
- Dark Blue Grey #1F3B4D ΔE 0.034
- Gunmetal #293241 ΔE 0.034
- Charcoal #264653 ΔE 0.044
- Space Cadet #2B2D42 ΔE 0.049
- Midnight Green #073B4C ΔE 0.049
- Dark Grey Blue #29465B ΔE 0.051
- Prussian Blue #1D3557 ΔE 0.057
More about Onyx
How to make Onyx
A starting recipe from common paint colors, found with a spectral paint model (the color mixer’s paint mode). Real pigments vary, so mix a small test batch and adjust.
- 2 parts gray
- 1 part black
Recipe result: #3C3C3C, a difference of ΔE 0.018 from Onyx. That is very close: most people will not see the difference.
Codes for Onyx in every format
| HEX | #343A40 |
| RGB | rgb(52, 58, 64) |
| HSL | hsl(210, 10%, 23%) |
| OKLCH | oklch(34.5% 0.013 248.2) |
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 #343A40 | 11.50:1 | AAA | Lc -100.2 | Preferred for body text |
| Black text on #343A40 | 1.82:1 | Fails | Lc 7.4 | Not readable |
| #343A40 text on white | 11.50:1 | AAA | Lc 96.5 | Preferred for body text |
| #343A40 text on black | 1.82:1 | Fails | Lc 0.0 | Not readable |
Shades and tints of Onyx
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
#F5F5F6
oklch(97% 0.001 286.4)
-
Step 100
100
#E8EAEC
oklch(93.6% 0.003 247.9)
-
Step 200
200
#D6D9DD
oklch(88.4% 0.006 255.5)
-
Step 300
300
#BCC1C7
oklch(80.9% 0.01 252.8)
-
Step 400
400
#99A2AA
oklch(70.8% 0.016 244.8)
-
Step 500
500
#808B96
oklch(63.1% 0.021 248.2)
-
Step 600
600
#697580
oklch(55.6% 0.022 245.9)
-
Step 700
700
#58626C
oklch(49.1% 0.02 248.2)
-
Step 800
800
#485058
oklch(42.7% 0.017 248.2)
-
Step 900
900 (this color)
#343A40
oklch(34.5% 0.013 248.2)
-
Step 950
950
#23272A
oklch(27% 0.008 240.2)
Onyx 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) | #383A40 | 0.007 |
| Deuteranopia (no green cones) | #363940 | 0.004 |
| Tritanopia (no blue cones) | #313B3C | 0.010 |
| Achromatopsia (no color) | #393939 | 0.013 |
Use Onyx 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.