Edit in JSFiddle

<!-- FOR DEMO PURPOSE-->
<section>
  <div class="container-fluid p-5 text-center">
    <!-- FOR DEMO PURPOSE -->
    <div class="row mb-5">
      <div class="col-lg-5 mx-auto">
        <h1 class="font-weight-bold">Circle Buttons</h1>
        <p class="text-muted">Create your own circle buttons with icons in Bootstrap&nbsp;4. <a href="https://bootstrapious.com/snippets" class="text-muted">Bootstrap snippet by Bootstrapious</a></p>
      </div>
    </div>
    <!-- END -->


    <div class="row align-items-stretch">

      <div class="col-lg-5 mb-4">
        <div class="bg-white p-4 rounded shadow-sm h-100">
          <h4 class="mb-4">Small circle buttons</h4>
          <!-- sm circle button-->
          <button class="btn btn-success btn-circle btn-circle-sm m-1"><i class="fa fa-check"></i></button>
          <button class="btn btn-primary btn-circle btn-circle-sm m-1"><i class="fa fa-cog"></i></button>
          <button class="btn btn-info btn-circle btn-circle-sm m-1"><i class="fa fa-paper-plane"></i></button>
          <button class="btn btn-warning btn-circle btn-circle-sm m-1"><i class="fa fa-tags"></i></button>
          <button class="btn btn-danger btn-circle btn-circle-sm m-1"><i class="fa fa-sliders"></i></button>
          <button class="btn btn-dark btn-circle btn-circle-sm m-1"><i class="fa fa-search"></i></button>
          <button class="btn btn-secondary btn-circle btn-circle-sm m-1"><i class="fa fa-wrench"></i></button>
          <button class="btn btn-light btn-circle btn-circle-sm m-1"><i class="fa fa-bar-chart"></i></button>
        </div>
      </div>

      <div class="col-lg-7 mb-4">
        <div class="bg-white p-4 rounded shadow-sm h-100">
          <h4 class="mb-4">Regular circle buttons</h4>
          <!-- regular circle buttons-->
          <button class="btn btn-success btn-circle m-1"><i class="fa fa-check"></i></button>
          <button class="btn btn-primary btn-circle m-1"><i class="fa fa-cog"></i></button>
          <button class="btn btn-info btn-circle m-1"><i class="fa fa-paper-plane"></i></button>
          <button class="btn btn-warning btn-circle m-1"><i class="fa fa-tags"></i></button>
          <button class="btn btn-danger btn-circle m-1"><i class="fa fa-sliders"></i></button>
          <button class="btn btn-dark btn-circle m-1"><i class="fa fa-search"></i></button>
          <button class="btn btn-secondary btn-circle m-1"><i class="fa fa-wrench"></i></button>
          <button class="btn btn-light btn-circle m-1"><i class="fa fa-bar-chart"></i></button>
        </div>
      </div>

      <div class="col-lg-12 mb-4">
        <div class="bg-white p-4 rounded shadow-sm h-100">
          <h4 class="mb-4">Large circle buttons</h4>
          <!-- lg circle buttons-->
          <button class="btn btn-success btn-circle btn-circle-lg m-1"><i class="fa fa-check"></i></button>
          <button class="btn btn-primary btn-circle btn-circle-lg m-1"><i class="fa fa-cog"></i></button>
          <button class="btn btn-info btn-circle btn-circle-lg m-1"><i class="fa fa-paper-plane"></i></button>
          <button class="btn btn-warning btn-circle btn-circle-lg m-1"><i class="fa fa-tags"></i></button>
          <button class="btn btn-danger btn-circle btn-circle-lg m-1"><i class="fa fa-sliders"></i></button>
          <button class="btn btn-dark btn-circle btn-circle-lg m-1"><i class="fa fa-search"></i></button>
          <button class="btn btn-secondary btn-circle btn-circle-lg m-1"><i class="fa fa-wrench"></i></button>
          <button class="btn btn-light btn-circle btn-circle-lg m-1"><i class="fa fa-bar-chart"></i></button>
        </div>
      </div>

      <div class="col-lg-12 mb-4">
        <div class="bg-white p-4 rounded shadow-sm h-100">
          <h4 class="mb-4">Xl circle buttons</h4>
          <!-- xl circle buttons-->
          <button class="btn btn-success btn-circle btn-circle-xl m-1"><i class="fa fa-check"></i></button>
          <button class="btn btn-primary btn-circle btn-circle-xl m-1"><i class="fa fa-cog"></i></button>
          <button class="btn btn-info btn-circle btn-circle-xl m-1"><i class="fa fa-paper-plane"></i></button>
          <button class="btn btn-warning btn-circle btn-circle-xl m-1"><i class="fa fa-tags"></i></button>
          <button class="btn btn-danger btn-circle btn-circle-xl m-1"><i class="fa fa-sliders"></i></button>
          <button class="btn btn-dark btn-circle btn-circle-xl m-1"><i class="fa fa-search"></i></button>
          <button class="btn btn-secondary btn-circle btn-circle-xl m-1"><i class="fa fa-wrench"></i></button>
          <button class="btn btn-light btn-circle btn-circle-xl m-1"><i class="fa fa-bar-chart"></i></button>
        </div>
      </div>
    </div>
  </div>
</section>
/*
*
* ==========================================
* CUSTOM UTIL CLASSES
* ==========================================
*
*/

.btn-circle {
  width: 45px;
  height: 45px;
  line-height: 45px;
  text-align: center;
  padding: 0;
  border-radius: 50%;
}

.btn-circle i {
  position: relative;
  top: -1px;
}

.btn-circle-sm {
  width: 35px;
  height: 35px;
  line-height: 35px;
  font-size: 0.9rem;
}

.btn-circle-lg {
  width: 55px;
  height: 55px;
  line-height: 55px;
  font-size: 1.1rem;
}

.btn-circle-xl {
  width: 70px;
  height: 70px;
  line-height: 70px;
  font-size: 1.3rem;
}

/*
*
* ==========================================
* FOR DEMO PURPOSES
* ==========================================
*
*/

body {
  background: #f8f8fd;
  color: #514B64;
  min-height: 100vh;
}