Percent pie chart with css only

Question

I've found pretty nice "percent pie chart" and want to create it with CSS only. No animation is required. Just static "picture".

I understand If I wanna create this kind of chart I need to use elements like these

The questions are

1. How to create element #2 ?
2. How to manage shape of element #2 for smaller (5%) or higher percent (80%) values ?

Answer 1

New answer 2021

With some modern techniques we can improve the code. You can have rounded edges and also consider animation:

@property --p{
  syntax: '<number>';
  inherits: true;
  initial-value: 1;
}

.pie {
  --p:20;      /* the percentage */
  --b:22px;    /* the thickness */
  --c:darkred; /* the color */
  --w:150px;   /* the size*/
  
  width:var(--w);
  aspect-ratio:1/1;
  position:relative;
  display:inline-grid;
  margin:5px;
  place-content:center;
  font-size:25px;
  font-weight:bold;
  font-family:sans-serif;
}
.pie:before,
.pie:after {
  content:"";
  position:absolute;
  border-radius:50%;
}
.pie:before {
  inset:0;
  background:
    radial-gradient(farthest-side,var(--c) 98%,#0000) top/var(--b) var(--b) no-repeat,
    conic-gradient(var(--c) calc(var(--p)*1%),#0000 0);
  -webkit-mask:radial-gradient(farthest-side,#0000 calc(99% - var(--b)),#000 calc(100% - var(--b)));
          mask:radial-gradient(farthest-side,#0000 calc(99% - var(--b)),#000 calc(100% - var(--b)));
}
.pie:after {
  inset:calc(50% - var(--b)/2);
  background:var(--c);
  transform:rotate(calc(var(--p)*3.6deg - 90deg)) translate(calc(var(--w)/2 - 50%));
}
.animate {
  animation:p 1s .5s both;
}
.no-round:before {
  background-size:0 0,auto;
}
.no-round:after {
  content:none;
}
@keyframes p{
  from{--p:0;}
}

body {
  background:#ddd;
}

<div class="pie" style="--p:20"> 20%</div>
<div class="pie" style="--p:40;--c:darkblue;--b:10px"> 40%</div>
<div class="pie no-round" style="--p:60;--c:purple;--b:15px"> 60%</div>
<div class="pie animate" style="--p:80;--c:orange;"> 80%</div>
<div class="pie animate no-round" style="--p:90;--c:lightgreen"> 90%</div>

Old answer

You can do this with multiple background.

From 0% to 50%:

.box {
  width: 100px;
  height: 100px;
  display: inline-block;
  border-radius: 50%;
  padding: 5px;
  background: 
    linear-gradient(#ccc, #ccc) content-box, 
    linear-gradient(var(--v), #f2f2f2 50%, transparent 0),
    linear-gradient(to right, #f2f2f2 50%, blue 0);
}

<div class="box" style="--v:-90deg"></div><!-- 0% -->
<div class="box" style="--v:-45deg"></div><!-- 12.5% -->
<div class="box" style="--v:  0deg"></div><!-- 25% -->
<div class="box" style="--v: 45deg"></div><!-- 37.5% -->
<div class="box" style="--v: 90deg"></div><!-- 50% -->

<p>The formula is [p = (18/5) * x - 90]. <small>Where x is the percentage and p the degree</small></p>
<p>for x = 5% --> p = -72deg </p>
<div class="box" style="--v:-72deg"></div>

From 50% to 100%:

.box {
  width:100px;
  height:100px;
  display:inline-block;
  border-radius:50%;
  padding:5px;
  background:
    linear-gradient(#ccc,#ccc) content-box,
    linear-gradient(var(--v), blue 50%,transparent 0),
    linear-gradient(to right, #f2f2f2 50%,blue 0);
}

<div class="box" style="--v:-90deg"></div><!-- 50% -->
<div class="box" style="--v:-45deg"></div><!-- 62.5% -->
<div class="box" style="--v:  0deg"></div><!-- 75% -->
<div class="box" style="--v: 45deg"></div><!-- 87.5% -->
<div class="box" style="--v: 90deg"></div><!-- 100% -->

<p>The formula is [p = (18/5) * x - 270]. <small>Where x is the percentage and p the degree</small></p>
<p>for x = 80% --> p = 18deg </p>
<div class="box" style="--v:18deg"></div>

You can combine both like this:

.box {
  width:100px;
  height:100px;
  display:inline-block;
  border-radius:50%;
  padding:5px;
  background:
    linear-gradient(#ccc,#ccc) content-box,
    linear-gradient(var(--v), #f2f2f2 50%,transparent 0) 0/calc(var(--s)*100%)      ,
    linear-gradient(var(--v), blue    50%,transparent 0) 0/calc((1 - var(--s))*100%),
    linear-gradient(to right, #f2f2f2 50%,blue 0);
}

<div class="box" style="--v:-90deg;--s:1"></div>
<div class="box" style="--v:0deg;--s:1"></div>
<div class="box" style="--v:90deg;--s:1"></div>
<div class="box" style="--v:0deg;--s:0"></div>
<div class="box" style="--v:90deg;--s:0"></div>

Now we can optimize like below to consider percetange value:

.box {
  
  --v:calc( ((18/5) * var(--p) - 90)*1deg);

  width:100px;
  height:100px;
  display:inline-block;
  border-radius:50%;
  padding:10px;
  background:
    linear-gradient(#ccc,#ccc) content-box,
    linear-gradient(var(--v), #f2f2f2     50%,transparent 0) 0/min(100%,(50 - var(--p))*100%),
    linear-gradient(var(--v), transparent 50%,blue        0) 0/min(100%,(var(--p) - 50)*100%),
    linear-gradient(to right, #f2f2f2 50%,blue 0);
}

<div class="box" style="--p:5;"></div>
<div class="box" style="--p:20;"></div>
<div class="box" style="--p:50;"></div>
<div class="box" style="--p:60;"></div>
<div class="box" style="--p:75;"></div>
<div class="box" style="--p:100;"></div>

Related question to get another version: Creating a static pie chart with CSS

---

We can also consider mask to add transparency:

.box {
  
  --v:calc( ((18/5) * var(--p) - 90)*1deg);

  width:100px;
  height:100px;
  display:inline-block;
  border-radius:50%;
  padding:10px;
  background:
    linear-gradient(var(--v), #f2f2f2     50%,transparent 0) 0/min(100%,(50 - var(--p))*100%),
    linear-gradient(var(--v), transparent 50%,blue        0) 0/min(100%,(var(--p) - 50)*100%),
    linear-gradient(to right, #f2f2f2 50%,blue 0);
  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite:destination-out;
  mask-composite:exclude;
}

body {
  background:linear-gradient(to right,red,yellow);
}

<div class="box" style="--p:5;"></div>
<div class="box" style="--p:20;"></div>
<div class="box" style="--p:50;"></div>
<div class="box" style="--p:60;"></div>
<div class="box" style="--p:75;"></div>
<div class="box" style="--p:100;"></div>

Also like below:

.box {
  
  --v:calc( ((18/5) * var(--p) - 90)*1deg);

  width:100px;
  height:100px;
  display:inline-block;
  border-radius:50%;
  padding:10px;
  background:
    linear-gradient(var(--v), transparent 50%,blue        0) 0/min(100%,(var(--p) - 50)*100%),
    linear-gradient(to right, transparent 50%,blue 0);
  -webkit-mask:
    linear-gradient(var(--v), #f2f2f2     50%,transparent 0) 0/min(100%,(50 - var(--p))*100%),
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite:destination-out;
  mask-composite:exclude;
}

body {
  background:linear-gradient(to right,red,yellow);
}

<div class="box" style="--p:5;"></div>
<div class="box" style="--p:20;"></div>
<div class="box" style="--p:50;"></div>
<div class="box" style="--p:60;"></div>
<div class="box" style="--p:75;"></div>
<div class="box" style="--p:100;"></div>

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