"Of course I know how to roll a joint," said Martha Stewart in 2013. But if she did it properly, how much pot would she use? A new study attempts to answer that question. Reporting in the journal Drug and Alcohol Dependence, the researchers point out that the quantity hasn't thus far been conclusively established, which presents a problem when it comes to things like "creating credible measures of marijuana consumption" and "projecting tax revenues post-legalization." Using nearly a decade's worth of data encompassing 10,628 marijuana transactions per federal arrest data, they concluded the average is 0.32 grams, at an average joint cost of $3.50. There are roughly 28 grams in an ounce, meaning an ounce of weed should yield about 88 joints.
The New York Times points out the question has been answered before, and those previous estimates have been higher: This 2011 study found the average to be 0.66 grams per joint (while noting blunts used even more, at 0.97 grams). A government report went with 0.43 grams, and a press release notes the Office of National Drug Control Policy uses 0.5 grams as its baseline. Two interesting sidenotes from the Times: First, the estimate isn't perfect—a point that researchers Greg Ridgeway and Beau Kilmer concede—because the data was sourced from a single group, those who have been arrested. It also notes that weight is just one part of the equation: How much THC is in the pot used to make the joint matters, too, in terms of understanding the health implications for users—and today's pot is much stronger than 1995's.