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Sterile Thaw Kingfisher

#39a4b0
Notes

Sterile Thaw Kingfisher (#39A4B0) is a true cyan with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (186°, 51%, 46%) 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
#39a4b0
RGB
rgb(57, 164, 176)
HSL
hsl(186, 51%, 46%)
HWB
hwb(186 22% 31%)
OKLCH
oklch(66.3% 0.096 205.7)
P3
color(display-p3 0.3484 0.6345 0.6821)
HSV
hsv(186, 68%, 69%)
LAB
lab(62.13% -26.11 -15.11)
LCH
lch(62.13% 30.16 210.06)
CMYK
cmyk(68%, 7%, 0%, 31%)

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.

Thaw
modifier

Old English thawian, to-melt-or-soften. As a color modifier, thaw implies a spring-melt-and-softening-frost quality, the visual register of English-spring-and-Pennine-thaw hand-spring-melt-and-softening-frost English-spring-and-Pennine-thaw-and-Cumbria-Highland-thaw thaw-and-spring-melt-and-softening-frost surfaces under English-spring-and-Pennine-thaw-and-Cumbria-Highland-thaw Yorkshire-Dales-and-Lake-District-and-Cairngorm spring-melt-light. Sits at the modifier-and-weather end of the grid, parallel to slush and rain in usage.

Kingfisher
noun

The family Alcedinidae — particularly Alcedo atthis, the European common kingfisher whose iridescent turquoise-blue plumage gives the color its name. The color refers to a male European kingfisher's wing: a saturated, slightly cool deep blue-green with the iridescent satin finish of structurally colored feathers.

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.

#39a4b0
Original
#979eb1
Protanopia
#8591b0
Deuteranopia
#00aba7
Tritanopia
#8e8e8e
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
2.95:1
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
7.11:1

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
##39A4B0
Display P3
Display P3
color(display-p3 0.3484 0.6345 0.6821)
P3 has subtle headroomOKLCH chroma 0.096

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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