Site concrete calculator - what mix is it for?

[BillySilly]

Hello
The site concrete calculator

http://www.diydoctor.org.uk/projects/mi ... Calculator
would be useful if I knew what proportions it was using!

Let me know if you do.
Even better do you have links to calculators for other concrete mixes and ones for cement and all-in aggregate?

If not, how do I work out the quantities for cement and all-in aggregate from this calculator?
Also if I am using for example 1:3 (cement:all-in aggregate) and the calculation was, for example, for 1:6 would I just double the figure for cement?