How to validate form controls data size not more than 2.5 mb?

How to validate form controls data size not more than 2.5 mb?

I have a form which has controls like first name, last name, etc and also file upload attachment. I need to calculated all the data should reach more than 2.5 mb. 

How can we do that with jQuery and show validation error on that page?
  2. form action="/ContactSubmission" class="form-horizontal" enctype="multipart/form-data" method="post" role="form" novalidate="novalidate">                  
  3.                    <div class="form-group">
  4.                         <div class="col-sm-5">
  5.                             <label class="control-label" for="FirstName">First Name</label><span class="red">*</span>
  6.                         </div>
  7.                         <div class="col-sm-7">
  8.                             <input class="form-control input-validation-error" data-val="true" data-val-required="The First Name field is required." id="FirstName" name="FirstName" placeholder="First Name" required="required" type="text" value="">
  9.                             <span class="field-validation-error" data-valmsg-for="FirstName" data-valmsg-replace="true" style="color:Red"><span for="FirstName" class="">The First Name field is required.</span></span>

  11.                         </div>
  12.                     </div>
  13.                     <div class="form-group">
  14.                         <div class="col-sm-5">
  15.                             <label class="control-label" for="LastName">Last Name</label><span class="red">*</span>
  16.                         </div>
  17.                         <div class="col-sm-7">
  18.                             <input class="form-control" data-val="true" data-val-required="The Last Name field is required." id="LastName" name="LastName" placeholder="Last Name" type="text" value="">
  19.                             <span class="field-validation-valid" data-valmsg-for="LastName" data-valmsg-replace="true" style="color:Red"></span>
  20.                         </div>
  21.                     </div>
  22.                     <div class="form-group">
  23.                         <div class="col-sm-5">
  24.                             <label class="control-label" for="EmailAddress">Email Address</label><span class="red">*</span>
  25.                         </div>
  26.                         <div class="col-sm-7">
  27.                             <input class="form-control" data-val="true" data-val-required="The Email Address field is required." id="EmailAddress" name="EmailAddress" placeholder="Email Address" type="text" value="">
  28.                             <span class="field-validation-valid" data-valmsg-for="EmailAddress" data-valmsg-replace="true" style="color:Red"></span>
  29.                         </div>
  30.                     </div>
  32.  <div class="form-group">
  33.                         <div class="col-sm-5">
  34.                             <label class="control-label-nobold" for="Attachement">Attachment</label>
  35.                         </div>
  36.                         <div class="col-sm-7">
  37.                             <input class="form-control" id="Attachement" name="Attachement" type="file" value="">

  39.                         </div>
  40.                     </div>
  42. <div class="form-group">
  43.                             <div class="col-sm-4 col-md-offset-5">
  44.                                 <button type="submit" class="btn btn-primary">Submit</button>

  46.                                 <button type="button" class="btn btn-default" id="cancel">Cancel</button>
  47.                             </div>
  48.                         </div>
  49. </form>