protected void Application_BeginRequest(object sender, EventArgs e)
{
    var cultureName = HttpContext.Current.Request.UserLanguages[0];
    Thread.CurrentThread.CurrentUICulture = new CultureInfo(cultureName);
}

<system.web>
  <!--If enableClientBasedCulture is true, ASP.NET can set the UI culture and culture for a Web page automatically, based on the values that are sent by a browser.-->
  <globalization enableClientBasedCulture="true" culture="auto:en-US" uiCulture="auto:en"/>