From Facebook page Australian Handspinners and Knitters Group.
There’s a lot of variables, but taking a medium wool breed such as the Corriedale, not coated, with a good clean sound fleece. Say 4kg raw. You will lose 20-25% of the weight while processing, you would be likely to end up with approximately 3kg of 8 ply. A large man’s plain jumper uses about 800grams of commercial 8 ply.