Ring-shaped process spinner with fading gradient effect around the ring

Question

I want to create a ring-shaped process spinner with CSS3 or JavaScript, similar to the loading progress spinner in Android.

The spinner should rotate continuously and be filled with a solid colour that fades out along the rim (i.e. a conical gradient) as in this picture:

How can I achieve this?

Anastomosis

possible duplicate of https://mcmap.net/q/92677/-how-to-do-gradient-borders-in-css – Hypothec

thanks, but i need a way to animate circle color like infinite process bar – Anastomosis

Why not use this picture and animate its rotation? Example for -webkit browsers – Unanimous

Something like this? jsfiddle.net/Qa3F9 for reference you can see this --> codepen.io/Zeneraith/pen/bdEmA – Anaximander

@Unanimous Thanks, That's so helpful, My question is: is that a way to create this in css3 or jquery, i want rotate like that image but when circle rotate hide half of border with fade and effect – Anastomosis

@VikasGhodke Good refrence, Thank you – Anastomosis

@C-link Unfortunately, the answer to that question won't work for this one; the asker is essentially looking for a partially occluded conical gradient, not a repeating linear gradient. – Gynecic

Answer 1

This would be trivially easy if only CSS or SVG had conical gradients! Until the conic-gradient() notation matures and gains support, we can approximate the effect by slicing up the gradient and covering the seams somehow.

Below you will find two solutions. The first solution uses an embedded SVG image; the second uses multiple CSS gradients and pseudo-elements.

Both start with a single div with a keyframe animation applied to make it rotate:

HTML:

<div class="spinner"></div>

CSS:

@keyframes rotate {
    from { transform: rotate(0deg);   }
    to   { transform: rotate(360deg); }
}

.spinner {
    animation: rotate 1s linear infinite;
    height: 200px;
    width: 200px;
}

You can use a progress element if you prefer, but you will find it a pain to style. Also note that unless you're using something like prefixfree.js, you'll need to add the vendor-prefixed versions of the @keyframes at-rule and the transform and animation properties.

---

The SVG solution

@keyframes rotate {
    from { transform: rotate(0deg);   }
    to   { transform: rotate(360deg); }
}

.spinner {
    animation: rotate 1s linear infinite;
    background: url('data:image/svg+xml;base64,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') no-repeat;
    height: 200px;
    width: 200px;
}

<div class="spinner"></div>

Tested and working in IE 10, Chrome and Firefox.

Caveats

Changing the inner or outer radius of the ring is more painful than you might imagine, as it would require editing the clip path values. It's outside the scope of this answer to explain how to calculate it, but suffice to say it took a bit of geometry. I'll try to put a generator on GitHub if I get time.

How the SVG version works

That big blob of gibberish is just a Base64 encoded SVG image. Run it through a Base64 decoder and you'll see the original SVG image.

Here's the full image nicely indented and commented so you can see exactly how it works:

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0,0 200,200">
    <defs>

        <!-- Ring shape centred on 100, 100 with inner radius 90px, outer
             radius 100px and a 12 degree gap at 348. -->
        <clipPath id="ring">
            <path d="M 200, 100
                     A 100, 100, 0, 1, 1, 197.81, 79.21
                     L 188.03, 81.29
                     A 90, 90, 0, 1, 0, 190, 100 z"/>
        </clipPath>

        <!-- Very simple Gaussian blur, used to visually merge sectors. -->
        <filter id="blur" x="0" y="0">
            <feGaussianBlur in="SourceGraphic" stdDeviation="3" />
        </filter>

        <!-- A 12 degree sector extending to 150px. -->
        <path id="p" d="M 250, 100
                        A 150, 150, 0, 0, 1, 246.72, 131.19
                        L 100, 100
                        A 0, 0, 0, 0, 0, 100, 100 z" fill="cyan"/>
    </defs>

    <!-- Clip the blurred sectors to the ring shape. -->
    <g clip-path="url(#ring)">

        <!-- Blur the sectors together to make a smooth shape and rotate
             them anti-clockwise by 6 degrees to hide the seam where the
             fully opaque sector blurs with the fully transparent one. -->
        <g filter="url(#blur)" transform="rotate(-6 100 100)">

            <!-- Each successive sector increases in opacity and is rotated
                 by a further 12 degrees. -->
            <use xlink:href="#p" fill-opacity="0"    transform="rotate(  0 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.03" transform="rotate( 12 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.07" transform="rotate( 24 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.1"  transform="rotate( 36 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.14" transform="rotate( 48 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.17" transform="rotate( 60 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.2"  transform="rotate( 72 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.24" transform="rotate( 84 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.28" transform="rotate( 96 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.31" transform="rotate(108 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.34" transform="rotate(120 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.38" transform="rotate(132 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.41" transform="rotate(144 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.45" transform="rotate(156 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.48" transform="rotate(168 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.52" transform="rotate(180 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.55" transform="rotate(192 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.59" transform="rotate(204 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.62" transform="rotate(216 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.66" transform="rotate(228 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.69" transform="rotate(240 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.7"  transform="rotate(252 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.72" transform="rotate(264 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.76" transform="rotate(276 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.79" transform="rotate(288 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.83" transform="rotate(300 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.86" transform="rotate(312 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.93" transform="rotate(324 100 100)"/>
            <use xlink:href="#p" fill-opacity="0.97" transform="rotate(336 100 100)"/>
            <use xlink:href="#p" fill-opacity="1"    transform="rotate(348 100 100)"/>
        </g>
    </g>
</svg>

This is minified, Base64 encoded and used as an inline CSS background image. You may also serve it as a separate file if you prefer. Technically, it should be possible to embed the image without the Base64 encoding, but right now that only works in Chrome.

---

The pure CSS solution

This solution uses separate linear gradients in each quadrant and relies on visual similarity to cover up the seams. The ring shape is formed using pseudo-elements.

@keyframes rotate {
    from { transform: rotate(0deg);   }
    to   { transform: rotate(360deg); }
}

.spinner {
    animation: rotate 1s linear infinite;
    background: cyan;
    border-radius: 50%;
    height: 200px;
    width: 200px;
    position: relative;
}

.spinner::before,
.spinner::after {
    content: '';
    position: absolute;
}

.spinner::before {
    border-radius: 50%;
    background:
        linear-gradient(0deg,   hsla(0, 0%, 100%, 1  ) 50%, hsla(0, 0%, 100%, 0.9) 100%)   0%   0%,
        linear-gradient(90deg,  hsla(0, 0%, 100%, 0.9)  0%, hsla(0, 0%, 100%, 0.6) 100%) 100%   0%,
        linear-gradient(180deg, hsla(0, 0%, 100%, 0.6)  0%, hsla(0, 0%, 100%, 0.3) 100%) 100% 100%,
        linear-gradient(360deg, hsla(0, 0%, 100%, 0.3)  0%, hsla(0, 0%, 100%, 0  ) 100%)   0% 100%
    ;
    background-repeat: no-repeat;
    background-size: 50% 50%;
    top: -1px;
    bottom: -1px;
    left: -1px;
    right: -1px;
}

.spinner::after {
    background: white;
    border-radius: 50%;
    top: 3%;
    bottom: 3%;
    left: 3%;
    right: 3%;
}

<div class="spinner"></div>

Tested and working in IE 10, Chrome and Firefox.

Caveats

Unlike the SVG solution, this only works against a solid background colour. It also requires modification in several places if you want to change that colour, which is a pain.

How the pure CSS version works

1. To start with, the spinner is styled as a circle with a uniform background colour. This will be the colour of the spinning gradient.

   .spinner {
       background: cyan;
       border-radius: 50%;
       /* ... */
   }
   

2. Set things up so that we can overlay the pseudo-elements on top of the spinner:

   .spinner {
       /* ... */
       position: relative;
   }
   
   .spinner::before,
   .spinner::after {
       content: '';
       position: absolute;
   }
   

3. This is the tricky bit. Each quadrant of the :before pseudo-element is set to a different linear gradient starting with opaque white and progressively becoming more and more transparent. Towards the centre it's easy to see where the gradients join up, but notice how around the outside the colours are close enough together that they appear to join up smoothly.

   .spinner::before {
       border-radius: 50%;
       background:
           linear-gradient(0deg,   hsla(0, 0%, 100%, 1  ) 50%, hsla(0, 0%, 100%, 0.9) 100%)   0%   0%,
           linear-gradient(90deg,  hsla(0, 0%, 100%, 0.9)  0%, hsla(0, 0%, 100%, 0.6) 100%) 100%   0%,
           linear-gradient(180deg, hsla(0, 0%, 100%, 0.6)  0%, hsla(0, 0%, 100%, 0.3) 100%) 100% 100%,
           linear-gradient(360deg, hsla(0, 0%, 100%, 0.3)  0%, hsla(0, 0%, 100%, 0  ) 100%)   0% 100%
       ;
       background-repeat: no-repeat;
       background-size: 50% 50%;
       top: -1px;
       bottom: -1px;
       left: -1px;
       right: -1px;
   }
   

   This is positioned so that it goes slightly over the edge of the spinner because if we position it right to the edge a faint rim of the background colour is visible.

4. Finally, hide the middle bit using the ::after pseudo-element to make a ring shape:

   .spinner::after {
       background: white;
       border-radius: 50%;
       top: 3%;
       bottom: 3%;
       left: 3%;
       right: 3%;
   }
   

Et voilá!

Gynecic

@Anastomosis Glad it was useful! I've just added another solution that uses SVG, in case you're interested; this one is fully transparent, so you can use it on any background. :) – Gynecic

awesome, very nice spinner. I'm struggling in making it thicker, tho. Any advice on how to handle that, please? – Ab

@Ab Hey David! Which spinner are you trying to make thicker? They both have some challenges; the SVG one would look great, but is fiddlier to edit (wish I'd written that generator!), while the pure CSS one is easy to edit—increase the top, bottom, left and right values for .spinner:after—but has some visible seams where the gradients join. (I should update it to use a conic gradient and the linear gradients as a backup…) – Gynecic

Hi @Jordan thx for your reply! I'm currently trying to edit the SVG one, since the CSS has some "transparency issues" in the middle (it actually looks good in the snippet since the ::after pseudo element has the same color as the background - white) .. looks like the world needs that generator :)) – Ab

Check my answer for a more easily customizable solution, including the stroke width. https://mcmap.net/q/225838/-ring-shaped-process-spinner-with-fading-gradient-effect-around-the-ring – Schulein

Answer 2

We can easily create this with only single div.

.loader {
  --border-width: 10px;
  
  height: 200px;
  width: 200px;
  border-radius: 50%;
  
  /* 0.5px's are needed to avoid hard-stopping */
  --mask: radial-gradient(
    farthest-side, 
    transparent calc(100% - var(--border-width) - 0.5px), 
    #000 calc(100% - var(--border-width) + 0.5px)
  );
  -webkit-mask: var(--mask);
          mask: var(--mask);
          
  /* we're using two half linear-gradient which is masked by the radial-gradient */
  background: linear-gradient(to top, rgba(0,255,226, 1), rgba(0,255,226, 0.5)) 100% 0/50% 100% no-repeat,
              linear-gradient(rgba(0,255,226, 0.5) 50%, transparent 95%) 0 0/50% 100% no-repeat;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

<div class="loader"></div>

And this is the comparison of my answer with @Jordan Gray's answer by setting background to body:

@Jordan Gray's answer:

body {
  background: pink;
}

@keyframes rotate {
    from { transform: rotate(0deg);   }
    to   { transform: rotate(360deg); }
}

.spinner {
    animation: rotate 1s linear infinite;
    background: cyan;
    border-radius: 50%;
    height: 200px;
    width: 200px;
    position: relative;
}

.spinner::before,
.spinner::after {
    content: '';
    position: absolute;
}

.spinner::before {
    border-radius: 50%;
    background:
        linear-gradient(0deg,   hsla(0, 0%, 100%, 1  ) 50%, hsla(0, 0%, 100%, 0.9) 100%)   0%   0%,
        linear-gradient(90deg,  hsla(0, 0%, 100%, 0.9)  0%, hsla(0, 0%, 100%, 0.6) 100%) 100%   0%,
        linear-gradient(180deg, hsla(0, 0%, 100%, 0.6)  0%, hsla(0, 0%, 100%, 0.3) 100%) 100% 100%,
        linear-gradient(360deg, hsla(0, 0%, 100%, 0.3)  0%, hsla(0, 0%, 100%, 0  ) 100%)   0% 100%
    ;
    background-repeat: no-repeat;
    background-size: 50% 50%;
    top: -1px;
    bottom: -1px;
    left: -1px;
    right: -1px;
}

.spinner::after {
    background: white;
    border-radius: 50%;
    top: 3%;
    bottom: 3%;
    left: 3%;
    right: 3%;
}

<div class="spinner"></div>

My answer:

body {
  background: pink;
}

.loader {
  --border-width: 10px;
  
  height: 200px;
  width: 200px;
  border-radius: 50%;
  
  /* 0.5px's are needed to avoid hard-stopping */
  --mask: radial-gradient(
    farthest-side, 
    transparent calc(100% - var(--border-width) - 0.5px), 
    #000 calc(100% - var(--border-width) + 0.5px)
  );
  -webkit-mask: var(--mask);
          mask: var(--mask);
          
  /* we're using two half linear-gradient which is masked by the radial-gradient */
  background: linear-gradient(to top, rgba(0,255,226, 1), rgba(0,255,226, 0.5)) 100% 0/50% 100% no-repeat,
              linear-gradient(rgba(0,255,226, 0.5) 50%, transparent 95%) 0 0/50% 100% no-repeat;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

<div class="loader"></div>

Blintze

This is much more versatile than my nearly 8-years-old approach! When I wrote my answer, CSS masking and custom properties were still in working draft—the latter was barely a year old. Things have really moved on, thank you for this really smart approach! – Gynecic

@JordanGray As a side note, now we have conical gradients... – Anhydrite

Answer 3

Using background-clip on single div:

div {
  margin: 0 auto;
  margin-top: 3rem;
}

.spnr {
  height: 100px;
  width: 100px;
  border-radius: 50%;
  border: 5px solid transparent;
  animation: spin 1s linear infinite;

  background: linear-gradient(white, white), conic-gradient(from 0.15turn, white, #00EBD3);
  background-origin: border-box;
  background-clip: content-box, border-box;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

<div class="spnr"></div>

---

More variations:

:root {
  --bg: white;
  --wbg: linear-gradient(var(--bg), var(--bg));
}

.dark>div {
  --bg: black;
  --wbg: linear-gradient(var(--bg), var(--bg));
}

.dark {
  background: black;
}

div {
  display: inline-block;
  margin: 0 1rem;
  margin-top: 0.5rem;
  height: 200px;
}

.one {
  background: var(--wbg), conic-gradient(from 0.15turn, transparent, #00EBD3);
}

.two {
  background: var(--wbg), conic-gradient(from 0.15turn, transparent, transparent, #00EBD3);
}

.three {
  background: var(--wbg), conic-gradient(from 0.15turn, transparent 0.0turn, transparent .04turn, pink 0.49turn, pink 0.5turn, transparent 0.50turn, transparent 0.55turn, pink 0.99999turn);
}

.four {
  background: var(--wbg), conic-gradient(from 0.25turn, transparent 0.0turn, darkgreen, transparent, darkgreen, transparent, darkgreen, transparent, darkgreen, transparent);
}

.five {
  background: var(--wbg), conic-gradient(from 0.25turn, transparent 0.0turn, red 0.125turn, transparent 0.125turn, red .25turn, transparent .25turn, red 0.375turn, transparent .375turn, red 0.5turn, transparent .5turn, red 0.625turn, transparent .625turn, red 0.75turn, transparent .75turn, red 0.875turn, transparent .875turn, red 1turn, transparent 1turn);
  animation-duration: 2s;
}

.six {
  border-width: 15px;
  background: var(--wbg), conic-gradient(from 0.25turn, transparent 0.0turn, transparent .125turn, orange 0.125turn, orange .25turn, transparent .25turn, transparent .375turn, orange 0.375turn, orange 0.5turn, transparent .5turn, transparent.625turn, orange .625turn, orange 0.75turn, transparent .75turn, transparent 0.875turn, orange .875turn, orange 1turn, transparent 1turn);
  opacity: 0.7;
}

.spnr {
  height: 60px;
  width: 60px;
  border-radius: 50%;
  border: 5px solid transparent;
  animation: spin 1s linear infinite;
  background-origin: border-box;
  background-clip: content-box, border-box;
}

.six {
  animation: size 2s linear infinite alternate;
}

.five {
  animation-duration: 2s;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

@keyframes size {
  0% {
    transform: rotate(0deg) scale(0.2);
    border-width: 5px;
  }
  100% {
    border-width: 10px;
    transform: rotate(840deg) scale(1);
  }
}

<div>
  <div class="spnr one"></div>
  <div class="spnr two"></div>
  <div class="spnr three"></div>
  <div class="spnr four"></div>
  <div class="spnr five"></div>
  <div class="spnr six"></div>
</div>
<div class="dark">
  <div class="spnr one"></div>
  <div class="spnr two"></div>
  <div class="spnr three"></div>
  <div class="spnr four"></div>
  <div class="spnr five"></div>
  <div class="spnr six"></div>
</div>

Gingrich

Nice but these only works on a white background – Thorson

@Thorson good catch! Fixed in the second snippet. – Gingrich

Answer 4

conic-gradient with mask and no complex values:

.ring {
  width: 150px; /* the size */
  padding: 8px; /* the border */
  background: #07e8d6; /* the color */
  aspect-ratio: 1;
  border-radius: 50%;
  -webkit-mask:
    conic-gradient(#0000,#000),
    linear-gradient(#000 0 0) content-box;
  -webkit-mask-composite: source-out;
          mask-composite: subtract;
  box-sizing: border-box;
  animation:r 2s linear infinite;
}

@keyframes r {to{transform:rotate(1turn)}}


body {
 background:linear-gradient(90deg,pink,#fff);
}

<div class="ring"></div>

Canale

Answer 5

I was able to create a real, full circle, gradient spinner, with opacity, by using a linear gradient on two half circles, and aligning them. No JavaScript or CSS necessary.

<svg
    version="1.1"
    width="24" height="24"
    viewBox="-1 -1 25 25"
    xmlns="http://www.w3.org/2000/svg"
>
    <defs>
        <linearGradient x1="0%" y1="0%" x2="100%" y2="0" id="gradient-1">
            <stop stop-color="red" offset="0%" />
            <stop stop-color="red" offset="63.1%" stop-opacity=".631" />
            <stop stop-color="red" offset="100%" stop-opacity=".5" />
        </linearGradient>
        <linearGradient x1="0%" y1="0%" x2="100%" y2="0" id="gradient-2">
            <stop stop-color="red" offset="0%" stop-opacity=".5" />
            <stop stop-color="red" offset="63.1%" stop-opacity=".12" />
            <stop stop-color="red" offset="100%" stop-opacity="0" />
        </linearGradient>
    </defs>
    <g fill="none">
        <g transform="translate(1 1)">
            <path
                d="M 10.5 10.5 m -10.5 0a 10.5 10.5 0 1 0 21 0a"
                stroke="url(#gradient-1)"
                stroke-width="3"
            />
            <animateTransform
                attributeName="transform"
                type="rotate"
                from="0 10.5 10.5"
                to="360 10.5 10.5"
                dur="1s"
                repeatCount="indefinite"
            />
        </g>
        <g transform="translate(1 1)">
            <path
                d="M 10.5 10.5 m -10.5 0a 10.5 10.5 0 1 0 21 0a"
                stroke="url(#gradient-2)"
                stroke-width="3"
            />
            <animateTransform
                attributeName="transform"
                type="rotate"
                from="-180 10.5 10.5"
                to="180 10.5 10.5"
                dur="1s"
                repeatCount="indefinite"
            />
        </g>
    </g>
</svg>

Schulein