How do you get the file size in C#?

FileInfo.Length will return the length of file, in bytes (not size on disk), so this is what you are looking for, I think.

FileInfo.Length will do the trick (per MSDN it "[g]ets the size, in bytes, of the current file.") There is a nice page on MSDN on common I/O tasks.

MSDN FileInfo.Length says that it is "the size of the current file in bytes."

My typical Google search for something like this is: msdn FileInfo

If you have already a file path as input, this is the code you need:

long length = new System.IO.FileInfo(path).Length;