If all you want to do is check it out online I would use the Berger bullets program, enter you data and hold you cursor over the pressure and that will pop up a chart and you enter the pressure for your elevation. That and a temp give you a decent air density, then just change and see what it moves. It's going to be minimal to 800yrds.
JBM ballistics also does the same thing online.
If you want to buy a program, any one should easily do what your looking for, Loadbase 3.0 is good, Exbal is good, have yet to use the one for your phone but they seem decent.