in bootstrap 3.0 :
Set heights using classes like .input-lg, and set widths using grid column classes like .col-lg-*.
Example:
<div class="row">
<div class="col-xs-2">
<input type="text" class="form-control" placeholder=".col-xs-2">
</div>
<div class="col-xs-3">
<input type="text" class="form-control" placeholder=".col-xs-3">
</div>
<div class="col-xs-4">
<input type="text" class="form-control" placeholder=".col-xs-4">
</div>
</div>