How Much Weed Is in a Joint? Pot Experts Have a New Estimate
How much marijuana is in a typical joint? Believe it or not, the question has perplexed experts for years. A new study claims to have an accurate estimate based on federal arrest data, and it’s less than regular users think.
Arriving at a trustworthy estimate is important for many reasons, including informing policy makers, law enforcement officials, health care providers and researchers.
Casual and scientific analyses have yielded a wide range of guesses as to the average contents of a marijuana cigarette, whether purchased or prepared at home.
At least one study placed the typical weight at 0.66 grams. The federal government has said it is closer to 0.43 grams.
The estimates from pot smokers are, shall we say, higher: Roughly one in four people responding to an informal poll last year by High Times, the cannabis magazine, said a typical joint contained one gram of marijuana. But nearly as many said it contained half that amount. Perhaps it depends how you roll.
The actual average may be much less. The new study, an analysis of federal drug arrest data published in the journal Drug and Alcohol Dependence, found the average amount of weed in a joint to be much smaller than those estimates: just 0.32 grams.
Such estimates about more than better understanding a high. Many users report marijuana consumption in terms of joints smoked, a statistic that is useless to researchers, authorities or policy makers without an accurate approximation of what that means.
“In order to get good projections, you need to be able to turn those answers — ‘I’ve had one joint in the last 30 days’ — into a quantity,” said Greg Ridgeway, a professor of criminology and statistics at the University of Pennsylvania who helped write the study with Beau Kilmer, a director of the RAND Drug Policy Research Center.
“These estimates can be incorporated into drug policy discussions,” the two researchers wrote, “to produce better understanding about illicit marijuana markets, the size of potential legalized marijuana markets, and health and behavior outcomes.”
Their estimate is based on marijuana purchase data collected from interviews with people who were arrested from 2000 to 2003 and from 2007 to 2010 under a Department of Justice program. While the answers came in many forms, Dr. Ridgeway and Dr. Kilmer focused on the more than 10,000 responses in which marijuana was measured in grams, ounces or joints.
The average price per gram, they found, was $6.81; the average joint was $3.50.
They couldn’t stop there. Although dividing the joint price by the gram price yields a rough estimate of a joint’s weight — about half a gram — it ignores how prices vary by location, time and quantity.
Those factors can significantly influence the estimates. Bulk discounts, in particular, modulate price. For example, the average price per gram jumps to $9.30 if the analysis is limited to purchases of five grams or less.
“When people buy an ounce of marijuana, they get a real volume discount,” Dr. Ridgeway said.
To account for those variations, the researchers applied a mathematical drug pricing model to the data, yielding their answer of 0.32 grams in the average joint.
Dr. Kilmer and Dr. Ridgeway acknowledge that their estimate is imperfect. It reflects just one population of marijuana consumer — people who have been arrested — and only in a smattering of counties across the United States.
But it is a convincing measurement nonetheless. Indeed, in 2015 a global drug survey conducted by academics found that most users get about three joints from a single gram of marijuana, or roughly 0.33 grams per joint.
Of course, weight is just a piece of the puzzle. Tetrahydrocannabinol, or THC, the chemical that produces the main psychoactive effects of marijuana, matters. And, like weight, THC content fluctuates, too: In a 2014 report, the White House Office of National Drug Control Policy estimated that marijuana’s average THC content rose from roughly 5 percent in 2000 to 8 percent in 2010.
Data from drug-related arrests offered a new insight into a matter critical for marijuana research and drug policy.