SOURCE

var x = $('.box').height()
    console.log(x);

<div class="wrapper">
  <div class="box">
    box
  </div>  
</div>

<div class="wrapper">
  <div class="box2">
    box
  </div>  
</div>

.wrapper {
  margin-top: 100px;
  border: 1px solid red;
}
.box {
  width: 50%;
  margin-bottom: -25px;
  background-color: rgba(90, 243, 155, 0.8);
  height: 50px;
}

.box2 {
  width: 50%;
  margin-top: -25px;
  background-color: rgba(90, 243, 155, 0.8);
  height: 50px;
}