Wenas podrias usar el componente Chilkat
Chilkat
.Http http
= new Chilkat
.Http();
bool success;
// Any string unlocks the component for the 1st 30-days.
success = http.UnlockComponent("Anything for 30-day trial.");
if (success != true) {
MessageBox.Show(http.LastErrorText);
return;
}
Chilkat.HttpResponse resp = null;
resp = http.GetHead("http://www.chilkatsoft.com/download/ChilkatDotNet2.msi");
if (resp == null ) {
MessageBox.Show(http.LastErrorText);
}
else {
string sizeStr;
sizeStr = resp.GetHeaderField("Content-Length");
if (sizeStr == null ) {
MessageBox.Show("No content-length header field");
}
else {
// Show the size of the file.
// You may convert the size string to an integer...
MessageBox.Show(sizeStr);
}
}
PD: Código cojido a secas de la página oficial
Sí quieres descargar el componente
h**p://www.example-code.com/csharp/http_getDownloadSize.asp