Hi micah,

Add the below line in your web.config file.

<system.web>
    <!-- 1GB in kilobytes, default is 4096 kb or 4MB-->
    <httpRuntime maxRequestLength="1048576" />
  </system.web>
  <system.webServer>
    <security>
      <requestFiltering>
        <!-- 1GB in bytes, default is 30000000 or approx. 28.6102 Mb-->
        <requestLimits maxAllowedContentLength="1073741824" /> 
      </requestFiltering>
    </security>
  </system.webServer>

Note: maxAllowedContentLength is measured in bytes while maxRequestLength is measured in kilobytes, which is why the values differ in this config example. Both are equivalent to 1 GB.

Hi micah,

Refer the below article.

Validate (Check) File Size in KB, Dimensions (Height and Width) of an Image using CustomValidator in ASP.Net using C# and VB.Net