From my own experience, seems like a lot. In a residential area, with clusters of 2-storey houses in the vicinity, I managed to get as far as 600m before I get poor connection warnings on my app (and on a few occasions, complete disconnections for about 1-2 secs!). Taking off from a clearing surrounded by forests (but with some trees nearby), I could fly as far as 1.6km. Might possibly go further, but had not tried to.