Calculating Forex Volume

A little background… I have been using the ifc markets demo platform (and quite happy with it). I also write some custom php/javascript code to keep track of the markets for me.

I know most forex platforms have some volume indicators, but I’m interested in doing it myself (to really understand it, and integrate it into my scripts).

I see lots of tutorials on why volume is important in forex (and stocks), but not much on the math. (There also seems to be come confusion with Metatrader using the word volume in a different way for their calculations… but I haven’t really looked into that.)

Right now I am grabbing the price pairs about every minute from an api, which works for what I’m currently doing… but I’m wondering if I need to grab it more to calculate volume?

Can someone either explain the math behind forex volumes or point me to a good resource. (not what volumes are good for, but how to actually calculate them).

Thanks
Rob

This thread is packed with info:

In calculating volume the problem comes from having a non centralized market,