How much can I expect, roughtly..

This is my first start to finsih grow. I know pretty much everything except how much I can expect. Got 5 plants, only know one is female. Vegging still but plan to let them get to 18 to 20 inches then flower.. Using CFLs for veg and 400w HPS in a 3x3x6' room. Can anyone give me a rough idea of how much Im going to get? I know it depends on all sorts of things but atleast to be able to know that I should expect an ounce or a quarter or whatever would be nice...

Thanks

Four ounces.

Of course it depends on strain but at 20" then you should get at least an ounce.

You have to remember that a plant is probably going to double in size after you start the 12/12 flowering stage so figure 40".

That is a good size plant so 1 ounce to 2 ounces is not out of the question. Probably even more!