I cook for a 5 persons household, and I fill 4 to 5 1L Ziplock bags with vegetable peels, tips/tails and other "garbage", which I then turn into 1 to 2L of stock. We also eat a lot of pasta, and I make sure to keep the "skin" of parmeggiano or grana padano we eat, and throw it in there as well.

If you try it, you will likely be surprised by how mich usually gets thrown away.