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green · cool

#40f166

a balanced, electric green · cool · closest name: Spring Green

Token name suggestion: Signal Moss

RGB
64, 241, 102
HSL
133°, 86%, 60%
CMYK
73, 0, 58, 6
Luminance
0.6496

#40f166 is a balanced electric green, 133° on the wheel and 68/100 on the cool side. Put black text on it (13.99:1). As text it scores 1.50:1 on white — use #0A8925 instead. Nearest name is Spring Green, nearest Tailwind family is green.

hsl(133 86% 60%)rgb(64 241 102)Base step 500AAA inkCool

At a glance

Every number on this page in one read: what #40f166 is made of, how bright it looks, and which way it leans.

Hex
#40f166
Hue
133°
green
Saturation
86%
electric
Lightness
60%
balanced
Brightness
95%
HSV value
Perceived
75%
weighted brightness
Luminance
0.6496
WCAG relative
Temperature
Cool
68/100 cool
Color family
Green
Tone
Electric
Best ink
Black
13.99:1
Closest name
Spring Green
ΔE2000 4
Chroma
89.3
LCH, 0–130ish
OKLCH L
0.842
perceptual lightness
Tailwind
green
500 · ΔE 10.9
Web-safe
#33FF66
nearest of 216
Where it sits
Hue133° of 360°
Saturation86%
Lightness60%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #40f166.

Temperature
Warm ← → Cool68% cool

Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.

Luminance by channel
Red2%
Green97%
Blue1%

Green carries most of what the eye calls brightness — that is why WCAG weights it 0.7152.

Every format

HEX#40f166
HEX (8-digit)#40f166ff
RGBrgb(64, 241, 102)
RGBArgba(64, 241, 102, 1)
HSLhsl(133, 86%, 60%)
HSV / HSBhsv(133, 73%, 95%)
HWBhwb(133 25% 5%)
CMYKcmyk(73%, 0%, 58%, 6%)
LABlab(84.5 -71.4 53.7)
LCHlch(84.5 89.3 143.0)
OKLCHoklch(0.842 0.231 146.5)
XYZ (D65)xyz(35.97, 64.96, 23.21)
Decimal4256102
Display P3color(display-p3 0.251 0.945 0.400)
Web-safe#33FF66

Copy-ready code

every platformclick to select
/* CSS */
color: #40f166;
background-color: #40f166;
/* CSS custom property */
--brand: #40f166;
/* Tailwind (arbitrary) */
class="text-[#40f166] bg-[#40f166]"
/* SCSS */
$brand: #40f166;
/* SwiftUI */
Color(red: 0.251, green: 0.945, blue: 0.400)
/* UIKit */
UIColor(red: 0.251, green: 0.945, blue: 0.400, alpha: 1)
/* Android XML */
<color name="brand">#40F166</color>
/* Android Compose */
Color(0xFF40F166)
/* Flutter */
Color(0xFF40F166)
/* Python / OpenCV (BGR) */
(102, 241, 64)
/* Python / PIL (RGB) */
(64, 241, 102)
/* Java AWT */
new Color(64, 241, 102)
/* .NET */
Color.FromArgb(255, 64, 241, 102)
/* OpenGL / Unity (0–1) */
(0.2510f, 0.9451f, 0.4000f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{64,241,102}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #40f166 85%, white);
border-color: color-mix(in oklab, #40f166 40%, transparent);
/* theme-aware in one line */
color: light-dark(#097720, #D3EED9);
/* relative colour syntax */
--hover: hsl(from #40f166 h s calc(l - 7));

Design tokens

The same ramp in the four formats a team actually needs. Paste one and the whole palette lands with it.

css custom propertiesclick to select
:root {
  --brand-50: #F2FDF4;
  --brand-100: #E5FAEA;
  --brand-200: #C5F7CF;
  --brand-300: #96F7AB;
  --brand-400: #62F381;
  --brand-500: #40f166;
  --brand-600: #11E43E;
  --brand-700: #0EBE34;
  --brand-800: #0B9829;
  --brand-900: #0D6E22;
  --brand-950: #084515;
  --brand: #40f166;
  --brand-ink: #000000;
  --brand-surface: #F4FAF6;
  --brand-border: #C0EDC9;
  --brand-hover: #1FEF4B;
  --brand-pressed: #10DA3B;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #142417;
    --brand-ink: #D3EED9;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F2FDF4',
        100: '#E5FAEA',
        200: '#C5F7CF',
        300: '#96F7AB',
        400: '#62F381',
        500: '#40f166',
        600: '#11E43E',
        700: '#0EBE34',
        800: '#0B9829',
        900: '#0D6E22',
        950: '#084515',
        DEFAULT: '#40f166',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F2FDF4,
  '100': #E5FAEA,
  '200': #C5F7CF,
  '300': #96F7AB,
  '400': #62F381,
  '500': #40f166,
  '600': #11E43E,
  '700': #0EBE34,
  '800': #0B9829,
  '900': #0D6E22,
  '950': #084515,
);
$brand-base: #40f166;
$brand-ink: #000000;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F2FDF4", "$type": "color" },
      "100": { "$value": "#E5FAEA", "$type": "color" },
      "200": { "$value": "#C5F7CF", "$type": "color" },
      "300": { "$value": "#96F7AB", "$type": "color" },
      "400": { "$value": "#62F381", "$type": "color" },
      "500": { "$value": "#40f166", "$type": "color" },
      "600": { "$value": "#11E43E", "$type": "color" },
      "700": { "$value": "#0EBE34", "$type": "color" },
      "800": { "$value": "#0B9829", "$type": "color" },
      "900": { "$value": "#0D6E22", "$type": "color" },
      "950": { "$value": "#084515", "$type": "color" }
    },
    "brandInk": { "$value": "#000000", "$type": "color" }
  }
}

Best text color

Only one of black and white can be right. This is the one, with the number that proves it.

Readable at a glance#000000 on #40f166 · 13.99:1
Use #000000AAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 1.50:1
AA fail · AA large fail · AAA fail
Aa
Black text · 13.99:1 · recommended
AA pass · AA large pass · AAA pass
Reading the other direction: #40f166 as text scores 1.50:1 on white and 13.99:1 on black.
Best tinted ink on it, if plain black or white feels flat: #097720 at 3.81:1.

Make it accessible

A contrast checker tells you that you failed. This tells you what to ship instead — same hue, same saturation, lightness moved only as far as WCAG demands.

The quick fox
#0A8925 · 4.55:1
AA on white−31% L
#0A8925
The quick fox
#07631B · 7.47:1
AAA on white−39% L
#07631B
The quick fox
#40f166 · 13.99:1
AA on blackalready passes
#40f166
The quick fox
#40f166 · 13.99:1
AAA on blackalready passes
#40f166

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #0DAA2E is enough for headings on white. Non-text elements such as icons, chart strokes and focus rings also sit at 3:1 under WCAG 2.2 (1.4.11).

Accessibility — WCAG contrast

Aa
#40f166 on white: 1.50:1
AA ✗ fail · AA-large · AAA
Aa
#40f166 on black: 13.99:1
AA ✓ pass · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #40f166 as text on that neutral, and that neutral as text on #40f166.

NeutralRatioBoth directions
White1.50:1AaAa
Slate 501.43:1AaAa
Slate 1001.37:1AaAa
Slate 2001.22:1AaAa
Slate 3001.01:1AaAa
Slate 4001.71:1AaAa
Slate 5003.17:1AaAa
Slate 6005.05:1AaAa
Slate 7006.90:1AaAa
Slate 8009.75:1AaAa
Slate 90011.89:1AaAa
Black13.99:1AaAa
Colour vision deficiency
true color
protanopia · #F4DB58
deuteranopia · #E0CD71
tritanopia · #00EBD3

Roughly one man in twelve has some form of colour vision deficiency. If any of the three panels above is hard to tell apart from a neighbouring colour in your palette, add a shape, an icon or a label so the meaning does not rest on hue alone.

Color scale — 50 to 950

A Tailwind-shaped ramp built around this exact hex. #40f166 is pinned to step 500; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F2FDF4
#E5FAEA
#C5F7CF
#96F7AB
#62F381
#40f166
#11E43E
#0EBE34
#0B9829
#0D6E22
#084515
Base = 500Lightest = 50 · #F2FDF4Darkest = 950 · #084515Text step on white = 900
Perceptual ramp — OKLCH

The same eleven steps expressed in OKLCH, where equal lightness numbers actually look equally spaced. HSL ramps go muddy in the yellows and washed out in the blues; this one does not. Modern browsers render it natively — the hex ramp above is the fallback.

50100200300400500600700800900950
oklch tokensclick to select
:root {
  --brand-50: oklch(0.97 0.058 146.5);
  --brand-100: oklch(0.94 0.092 146.5);
  --brand-200: oklch(0.88 0.138 146.5);
  --brand-300: oklch(0.80 0.180 146.5);
  --brand-400: oklch(0.72 0.212 146.5);
  --brand-500: oklch(0.64 0.231 146.5);
  --brand-600: oklch(0.56 0.231 146.5);
  --brand-700: oklch(0.48 0.217 146.5);
  --brand-800: oklch(0.40 0.194 146.5);
  --brand-900: oklch(0.32 0.161 146.5);
  --brand-950: oklch(0.24 0.127 146.5);
}

Colors that work with #40f166

Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.

Text on it#000000
Black wins here
Surface#F4FAF6
Tinted page background
Border#C0EDC9
Hairlines and dividers
Muted text#4B9B5C
Captions on the surface
Accent#BC0AC2
Second voice, not a rival
Dark variant#097720
Hover, pressed, headers
Light variant#E7FDEC
Selected rows, tints
Dark surface#142417
Dark-mode background
Hover#1FEF4B
One step down in lightness
Pressed#10DA3B
Two steps down
Disabled#C6DBCB
Chroma pulled out
Focus ring#4AFC70
Offset from the fill so it reads
Light mode
Everything in its place

Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.

Primary actionSecondaryBadge
Dark mode
Same hue, inverted

Lightness flips, hue holds. The accent stays the anchor in both themes.

Primary actionSecondaryAccent

In real components

The same eight roles, wired into the interface patterns you will actually build with them. Every state below is a computed value, not a mock-up.

Buttons and states
Save changesHoverPressedDisabled
OutlineSubtleLinkFocused
Form field
you@company.com

Focus ring uses the light variant so the field still reads as one shape.

Send me product updates
Notice
Your export is ready

The file stays available for seven days. Download it before it expires.

NewBetaDraft
Data
Storage used68%
Acme LtdActive
NorthwindTrial
GlobexActive

How to use #40f166

Derived from its contrast, chroma and lightness — not from taste.

Works well for
  • Text and icons on dark surfaces
  • Primary buttons and calls to action
  • Focus rings, active and selected states
  • Brand accents, badges and data highlights
  • Chart series and data categories
Use with care
  • Text of any size on white — fails WCAG AA
  • Full-page backgrounds — tiring over long sessions
  • Status meaning — pair it with an icon or label, never colour alone
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
Not as text
Safe as a fill behind white type
No — use #097720
Safe as a 1px border on white
No — use #0DAA2E

Meaning and mood

What a colour in this family tends to signal, and how this particular chroma and lightness change the reading.

safegrowingnaturalpermissive

Green means go, well, and grown. It carries finance, sustainability and health with almost no explanation needed.

At this chroma the association is amplified — it will dominate anything placed beside it, so give it space and use it sparingly. The mid lightness keeps it versatile in both themes.

Worth knowing

Red/green pairs are the most common colour-blindness failure — never let the two carry meaning alone.

Reads as
  • FormalityLow
  • EnergyHigh
  • Weight40/100
  • TemperatureCool
  • ApproachabilityReserved

Colour associations are cultural and vary by market. Treat these as a starting point for a conversation with your audience, not a finding about them.

Similar colors

One move away from this hex in each direction. Every swatch is its own page.

Color relationships

The wheel positions with their names attached, so you can grab the one you actually need.

Complementary#F140CB
Analogous left#72F140
Analogous right#40F1BF
Split-complement 1#BF40F1
Split-complement 2#F14072
Triadic 1#6640F1
Triadic 2#F16640
Tetradic#4072F1
On the wheel
Base+30°−30°+120°+240°+180°133°

#40f166 sits at 133°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red25.1%
Green94.5%
Blue40.0%
R · 0–255
64
0x40
G · 0–255
241
0xf1
B · 0–255
102
0x66

CMYK percentages

Cyan73.4%
Magenta0.0%
Yellow57.7%
Key (black)5.5%

Total ink coverage is 137%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#40f166 text on a black background

contrast 13.99:1

Card sample

#40f166 text on a white background

contrast 1.50:1

Card sample

#40f166 on grey

1.37:1

#40f166 on its own surface

1.42:1

#40f166 on its dark surface

10.81:1

CSS3 live lab

Text font color

The quick brown fox

color: #40f166;
Background color
Panel with #40f166 background
background-color: #40f166;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #40f166;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(64, 241, 102, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(64, 241, 102, 0.45);
Border & gradient
Gradient panel
border: 3px solid #40f166;
background: linear-gradient(135deg, #40f166, #40F1DC);
Gradient text

Gradient headline

background: linear-gradient(90deg, #40f166, #40DAF1);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #40f166;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #40f166;
caret-color: #40f166;
Left rule
Pull quote or callout
border-left: 4px solid #40f166;
Ring + tint
Selected chip
background: #E7FDEC;
box-shadow: inset 0 0 0 2px #40f166;
Conic badge
68%
background: conic-gradient(#40f166 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #40f166 over white; the bottom row is the same alpha over a checkerboard, so you can see what survives on a photo or a video.

Bottom row of hexes is the flattened result over white — use those when a design tool refuses transparency, or when you need a solid fallback.

alpha in every syntaxclick to select
rgba(64, 241, 102, 0.5)
rgb(64 241 102 / 50%)
#40f16680
hsl(133 86% 60% / 50%)
color-mix(in srgb, #40f166 50%, transparent)
Alpha8-digit hexFlat on white
10%#40f1661a#ECFEF0
20%#40f16633#D9FCE0
40%#40f16666#B3F9C2
60%#40f16699#8CF7A3
80%#40f166cc#66F485

Gradients from #40f166

Six recipes, each built from this hex and shown with the exact CSS that produced it.

Elevation
Same hue, three lightnesses — safe anywhere
background: linear-gradient(135deg, #79F594, #40f166 45%, #097720);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #40f166, #24EFE8);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #40f166, #F140CB);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #96F7AB 0%, #40f166 45%, #097720 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4FAF6, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #A0F470 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #5DF3D5 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #097720 0%, transparent 65%), #40f166;

Monochromatic scale

Palettes built from #40f166

Shades — darker

Tints — lighter

Tones — desaturated

Color harmonies

Nearest named colors

Ranked with CIEDE2000 across all 139 CSS keywords. Under ΔE 2 the eye stops telling them apart; over ΔE 10 they are plainly different colors.

#40f166 in the real world

Where a color in this family tends to land, and the interface roles it is usually asked to play.

Industries
SustainabilityFinanceHealth and wellnessAgriculture
Common UI roles
ButtonsLinksFocus statesCharts
Print note

Sits outside most CMYK gamuts — expect a duller press result, or specify a spot ink.

On screens

Holds up across typical panel gamma. Still worth checking on an uncalibrated laptop, where mid-tones shift most.

In dark mode

Usable as-is on a dark surface at 13.99:1.

Explore nearby colors

Small, deliberate steps away from this hex — useful when you are hunting for the version of a colour that finally feels right.

#40f166, answered

What color is #40f166?

#40f166 is a balanced electric green, closest to Spring Green (ΔE2000 4). It sits at 133° on the hue wheel with 86% saturation and 60% lightness, which reads as cool.

What is the RGB value of #40f166?

rgb(64, 241, 102) — 64 red, 241 green and 102 blue out of 255, or 25.1% / 94.5% / 40% by channel.

What is #40f166 in HSL and HSV?

hsl(133, 86%, 60%) and hsv(133, 73%, 95%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #40f166 a light or a dark color?

It is a light color. Relative luminance is 0.6496 and perceived brightness is 75%, so black text on it reaches 13.99:1.

Should I use black or white text on #40f166?

Black. It scores 13.99:1 against #40f166, versus 1.50:1 for white — AAA at any size.

Is #40f166 accessible on a white background?

#40f166 on white scores 1.50:1, which fails WCAG AA at every size. Darken it to #0A8925 to reach 4.5:1, or #07631B for 7:1.

What is the complementary color of #40f166?

#F140CB sits directly opposite on the wheel. Softer options are the split-complements #BF40F1 and #F14072, which give the same contrast with far less vibration.

What colors go well with #40f166?

For interface work: #F4FAF6 as the surface, #C0EDC9 for borders, #4B9B5C for secondary text, #BC0AC2 as an accent and #097720 for hover and pressed states. For a palette, the analogous pair #72F140 and #40F1BF stays calm, while #F140CB is the loudest partner.

What is #40f166 in CMYK for printing?

cmyk(73%, 0%, 58%, 6%). This is a screen-to-ink approximation — a color this saturated sits outside most CMYK gamuts and will print duller than it looks here.

Is #40f166 warm or cool?

Cool — it scores 68 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #5BF140; nudged cooler, #3EF3A7.

Which Tailwind color is closest to #40f166?

The green family — its 500 step is #22c55e, ΔE2000 10.9 away. That is a visible difference, so define #40f166 as a custom token rather than reaching for the built-in.

How do I use #40f166 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#40f166] or text-[#40f166], or register the whole ramp under theme.extend.colors.brand so you get bg-brand-500 and friends. The generated 50–950 scale on this page is ready to paste into your config.

What is #40f166 with 50% opacity?

rgba(64, 241, 102, 0.5), or #40f16680 in eight-digit hex. Over white that composites to #A0F8B3; over black, #207933.

Is #40f166 a web-safe color?

No. The nearest web-safe colour is #33FF66, ΔE2000 3 away. The palette only matters for legacy displays and some email clients now.

What does the color #40f166 mean?

As a green, it reads safe, growing, natural. Green means go, well, and grown. It carries finance, sustainability and health with almost no explanation needed. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #40f166?

The safest is same-hue elevation: linear-gradient(135deg, #79F594, #40f166 45%, #097720). For more colour, a short hue run to #24EFE8 keeps it rich without turning muddy.

Work with #40f166 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #40f166 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.