You guys know you don't actually even have to sum all the parts right? Take two steps: Drain all the fuel from your tanks, take it to the launch pad, and look at its mass on the info tab from the orbit screen. Then, do the same thing when the tanks are full (or the other way around). These are your dry and total masses respectively. so it just boils down to plugging in dV=9.82*I_sp*ln(dry/total) Still harder probably slightly harder than mechjeb, but basically quick and easy.