How to set twitter bootstrap modal wider and higher?

If your modal id is "myModal "

You could try adding a style like:

#myModal 
{
    width: 700px; 
    margin-top: -300px !important;
    margin-left:  -350px !important; 
} 

#myModal .modal-body {
    max-height: 525px;
}

In Bootstrap 3.1.1 they added modal-lg and modal-sm classes. You control the modal size using @media queries like they do. This is a more global way of controlling the modal size.

@media (min-width: 992px) {
    .modal-lg {
        width: 900px;
        height: 900px; /* control height here */
    }
}

Sample code:

<!-- Large modal -->
<button class="btn btn-primary" data-toggle="modal" data-target=".bs-example-modal-lg">Large modal</button>

<div class="modal fade bs-example-modal-lg" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel" aria-hidden="true">
  <div class="modal-dialog modal-lg">
    <div class="modal-content">
      ...
    </div>
  </div>
</div>

<!-- Small modal -->
<button class="btn btn-primary" data-toggle="modal" data-target=".bs-example-modal-sm">Small modal</button>

<div class="modal fade bs-example-modal-sm" tabindex="-1" role="dialog" aria-labelledby="mySmallModalLabel" aria-hidden="true">
  <div class="modal-dialog modal-sm">
    <div class="modal-content">
      ...
    </div>
  </div>
</div>

The easiest way to do this is to use the .modal-lg. Add it to the modal-dialog class within the modal container like so:

<div class="modal fade">
    <div class="modal-dialog modal-lg" role="document">
            <div class="modal-content">
                I am now wider!
            </div>
    </div>
</div>