We recommend 85 grams (3 ounces) initially. In some cases you might want to bring that up to 90-100 grams, if the green coffee is moving sufficiently when you start the roast. You can always check whether there is too much coffee loaded in the roaster by running it in cooling mode a few seconds. Fan speed in cooling mode is same as fan speed on High during roasting. Our experience is that after a few batches, you will see a new machine start to rotate 90-100 grams easier. In fact we have had units where we can increase the batch size because of this. I think it's due to some "seasoning" of the roast chamber surface after a few batches that makes it "slicker", but I am not really sure! Here is a video shows good bean movement in Popper.