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Sterile Fast Turquoise

#42d6cd
Notes

Sterile Fast Turquoise (#42D6CD) is a true cyan with a cool character. It leans cool, sitting on the blue, green, and violet side of the wheel. Quiet and dependable, a fit for product UI and data visualization. Its HSL profile (176°, 64%, 55%) places it in the balanced band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary red. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#42d6cd
RGB
rgb(66, 214, 205)
HSL
hsl(176, 64%, 55%)
HWB
hwb(176 26% 16%)
OKLCH
oklch(79.8% 0.123 189.0)
P3
color(display-p3 0.4420 0.8277 0.8010)
HSV
hsv(176, 69%, 84%)
LAB
lab(78.26% -40.20 -6.86)
LCH
lch(78.26% 40.78 189.68)
CMYK
cmyk(69%, 0%, 4%, 16%)

Etymology

Sterile
adjective

Latin sterilis, barren / not-fertile — sharing root with Greek steiros (barren). As a color modifier, sterile implies a clear-and-medical-clean-and-stripped quality, the crisp color of operating-theater surgical-environment white-and-stainless-steel surfaces. Sits at the crisp-and-clean end of the grid, parallel to sanitary and hygienic in usage.

Fast
modifier

Old English fæst, abstinence-from-food. As a color modifier, fast implies a Lenten-and-fasting-and-restraint quality, the visual register of Roman-Catholic-and-Eastern-Orthodox-Fast Lenten-and-Ramadan-fasting religious-fast-and-restraint austere surfaces under fasting-and-restraint austere ecclesiastical light. Sits at the modifier-and-time end of the grid, parallel to lent and vigil in usage.

Turquoise
noun

The hydrated copper-aluminum phosphate mined in Persia and the American Southwest for thousands of years — the firuze of Iran, the chalchihuitl of Mesoamerica, the heart of Pueblo and Navajo silverwork. The color refers to a fine Sleeping Beauty turquoise from Arizona: a saturated, slightly green-shifted blue with the slight matrix of host-rock veining. Brighter than persian, lighter than cerulean.

Closest matches

The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.

Variations

Click any swatch to explore

Harmonies

Accessibility

Color-vision simulation

How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.

#42d6cd
Original
#cacbcd
Protanopia
#b5bbce
Deuteranopia
#00dbd3
Tritanopia
#b6b6b6
Achromatopsia
WCAG contrast

The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.

The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
Failon White
1.79:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAAon Black
11.73:1

Wide gamut

Display P3 representation

The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.

sRGB hex
sRGB hex
##42D6CD
Display P3
Display P3
color(display-p3 0.4420 0.8277 0.8010)
P3 has subtle headroomOKLCH chroma 0.123

Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.

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