So currently the Harry Potter characters are higher with spells in terms of Lifting Strength. However, there are quite some feats that can be calculate.
Harry Potter and the Prisoner of Azkaban Chapter 10 "The Marauder's Map"
|“||The Christmas tree beside their table rose a few inches off the ground, drifted sideways and landed with a soft thump right in front of their table, hiding them from view.||„|
So levitating a tree. That's at least Class 1.
Remus Lupin and Sirius Black both took turns levitating Severus Snape in the Harry Potter and the Prisoner of Azkaban. Voldemort also (possibly) used this to levitate Charity Burbage in Harry Potter and the Deathly Hallows. In Harry Potter and the Cursed Child (it is canon, google it), Draco Malfoy also used this to cause Harry Potter to bounce backwards. So that's Regular Human strength. Weak.
According to this, almost anything can be lifted with this spell, although the object levitated depends on the skill of the caster and the weight of the object. So we'll have to calc every single user one by one, we can't powerscale. Well only 3 users of this charm have profiles on this wiki.
Harry Potter used this spell to levitate a motorcycle side-car. Well, a motorcycle's just only Class 1, so I doubt the side-car would be any heavier than that. Probably Superhuman range.
Hermione levitated feathers, but that doesn't matter (like who cares about levitating feathers). The other time she used this spell was to move Ron Weasley. So that's Regular Human.
He used this to levitate a troll's club. Dunno how much is that. So Unknown.
EDIT: Class 5 via Kep's calc
Hermione Granger used this charm to levitate Harry Potter into his bed, and also to levitate a dresser off Ron. Don't know how heavy's a dresser though.
Can lift humans into the air, again.
Again, to knock humans off their feet.
Class 5 lifting strength