bulk is more of an issue than size or weight.....but a general rule of thumb, drop clothes loosely into tub until 2/3 full, for bst results, somewhat foolproof for most loads.....this is a general rule in laundromats, and what we had working in the laundry.....more of a set it and forget it...but like the others said, you can add clothes until the rollover slows, but doesn't stop....adding a few socks or washcloths wouldn't hurt a whole lot....a towel or pair of jeans may be a bit too much...