How Much Is An 8Th Of Weed In Grams? Posted on 28.05.2022Author Andrey KiligannPosted in CannabisLeave a Reply An eighth of an ounce weighs around 3.5 grams, which is only a hair more than the typical penny, which weighs 3 grams. An ounce is equal to roughly 3.5 grams.