The smallest scale is basically the same as for tokamaks (the advantage is that you can operate a stellarator continuously, while a tokamak is pulsed which may

The smallest scale is basically the same as for tokamaks (the advantage is that you can operate a stellarator continuously, while a tokamak is pulsed which may be less convenient for power generation). The scale is mostly limited by magnetic field strength. With ordinary superconducting magnets they get pretty big (the planned ITER reactor will weigh 5,116 tonnes). Some people say that new high-temperature superconductors will enable stronger magnets and hence smaller reactors (http://news.mit.edu/2017/brandon-sorbom-designing-fusion-future-0123 http://news.mit.edu/2017/brandon-sorbom-designing-fusion-fut...).