Determining buffer size when working with files in C#? [duplicate]

Question

I have this simple code which combines text files into one text file :

void Main()
{
const int chunkSize = 2 * 1024; // 2KB
var inputFiles = new[] { @"c:\1.txt", @"c:\2.txt", @"c:\3.txt" };
using (var output = File.Create(@"c:\output.dat"))
{
    foreach (var file in inputFiles)
    {
        using (var input = File.OpenRead(file))
        {
            var buffer = new byte[chunkSize];
            int bytesRead;
            while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0)
            {
                output.Write(buffer, 0, bytesRead);
            }
        }
    }
}
}

My question is about the chunkSize size.

How can I know if the number I've chosen is the right one ? (1024*2)

I'm trying to find the idle formula :

Assuming each file size is F mb , and I have R mb of Ram and the block size of my Hd is B kb - is there any formula which I can build to find the idle buffer size ?

Answer 1

4KB is a good choice. for more info look to this:
File I/O with streams - best memory buffer size

Greetings