Technically anything up to 1 HP but most can be programmed for 150% overload safely so it will run a 1 1/2 HP but may trip under hard load.

I have one of the 1 1/2Hp Chinese spindles here running off a 0.55Kw [ 3/4HP ] IMO Cub inverter, the cheap one, programmed for 150% overload and it runs fine with up to 6mm cutter in it.

Been running test cycles with this for about 4 hours, non stop at 24,000 rpm and no problem although it is a bit small and I wouldn't recommend it for continuous use or any larger cutter.