By default is 4 MB, if we need more just:

<system.web>
…
<httpRuntime targetFramework=”4.5.2″ maxRequestLength=”1048576″ executionTimeout=”3600″ />
…
</system.web>
<system.webServer>
…
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength=”1073741824″ />
</requestFiltering>
</security>
</system.webServer>