The measurement you gave, for it to be dead-on 1:18 scale, would need to be 16 inches tall on the droid...
That pic you just posted sort of changes the angles, so yeah, eyeballing it from that angle looks way different. Now I just don't know...
16 inches is a basic figure on top of a 12" figure or so (obviously), which doesn't look terribly tall to me, but that doesn't look 16" to me in the picture there for sure. Hmm... Not sure, and really still up in the air if I'm even buying. I could save a ton this year the way things are going though, hah.