How many grams in a CBD joint, and how long do 5 g last?

Nobody weighs their joints, and older estimates ranged from 0.3 to 1 g. Greg Ridgeway (University of Pennsylvania) and Beau Kilmer (RAND Corporation) came at the question through prices. They took 10,628 cannabis purchases reported between 2000 and 2010 by people arrested in the United States, both joints and loose herb. By linking the price paid to the weight bought, they put the average weight of a joint at 0.32 g, with an interval of 0.30 to 0.35 g. The study appeared in Drug and Alcohol Dependence.

That is less than the figures used until then: the White House drug policy office counted 0.5 g per joint, as the University of Pennsylvania's news release points out.

This benchmark has three limits. It concerns cannabis bought in the United States, not CBD flower in France. The weight is inferred from prices, not weighed. And it counts herb only: for the same size, a joint rolled with tobacco holds less flower, and the more tobacco, the less flower. See our alternatives to tobacco in a joint. From here on, 0.32 g is the basis for the arithmetic; weigh one of your own joints to redo the sums with your own figure.

The percentage shown on a product page is a share of the dry flower's weight. A flower at 11% CBD contains 110 mg of CBD per gram. The calculation is a single multiplication: joint weight × percentage.

Use the percentage measured on the batch, not the one in the product name. On 24 September 2026, the Sour Spritz page shows 12.9% CBD measured for a name that says 15%, and the Strawnana page shows 12.3% for a name that says 11%. The same calculation gives 41.3 mg and 39.4 mg of CBD per 0.32 g joint. These pages also list CBDA, the acid form of CBD, which heat partly turns into CBD.

Part of the CBD is lost in the burning tip and in the smoke that is never inhaled. The share that reaches the circulation is called bioavailability, and for smoked CBD it rests on a single study. A systematic review published in 2018 in Frontiers in Pharmacology gathered the pharmacokinetic measurements of CBD in humans: 24 publications kept out of 792 screened. Only one reports a bioavailability. In 1986, five men smoked a cigarette containing 19.2 mg of CBD in a laboratory: on average 31% reached the blood, with a standard deviation of 13 points from one person to the next.

THC has been studied far more. A 2007 review puts its bioavailability by smoking at 2 to 56%. The author attributes part of that spread to how people smoke: the number, length and spacing of puffs, how long the smoke is held, and the volume inhaled. Nothing suggests CBD escapes this. The "about 11 mg" in the table is therefore an order of magnitude, not a measurement.

Going from an 8% flower to a 14% flower multiplies the CBD in the joint by 1.75. The way someone smokes can change the absorbed share far more, judging by the 2 to 56% measured for THC. The flower's percentage cannot set an amount to the milligram.

No authority sets an amount of smoked CBD either. The only official benchmark in Europe, about 2 mg a day for a 70 kg adult, published by EFSA on 9 February 2026, concerns CBD taken by mouth as a food supplement at least 98% pure. It applies neither to smoke nor to flower. Our article on EFSA's 2 mg benchmark sets out its limits. This guide describes amounts and does arithmetic; it does not recommend any amount to consume.

THC matters too. A flower at 0.30% Δ⁹-THC, the maximum set by the French order of 30 December 2021, contains up to 0.96 mg of it in a 0.32 g joint. Behind the wheel, article L235-1 of the French Highway Code punishes driving after drug use revealed by a test with three years in prison and a €9,000 fine, with no minimum threshold. Smoking is banned in places of collective use (article L3512-8 of the Public Health Code) and in a car with a minor present (article L3512-9). The full legal picture is in our article on smoking hemp and what the law says.

Divide the pouch weight by 0.32 to get the number of joints, then by your pace to get the duration. One gram makes a little over three joints.

The second column answers "how much for a month": from 1.4 to 19.2 g. With 0.5 g joints, multiply those grams by 1.56 and divide the durations by the same factor.

A 2 g pouch makes six 0.32 g joints, enough to try a variety. Larger pouches cost less per gram, but the flower ages while you finish it.

An Israeli study published in 2020 in Frontiers in Plant Science followed flowers stored for a year. The terpenoids, which carry the smell, had lost more than 50% within four months, whatever the storage temperature. Cannabinoids lost 26% on average over twelve months. At one joint a week, a 10 g pouch lasts 31 weeks, more than seven months: the end of the pouch will have lost much of its aroma. A simple rule follows: choose the pouch you will finish within four months at your own pace.

To slow that loss, keep the flowers whole, in a closed jar, away from light and somewhere cool. Our guide to storing CBD flowers gives the humidity range to aim for, 55 to 65%.

Price of a joint = price per gram × 0.32. On the Strawnana, Sour Spritz and Confidential Weed pages, the last measured at 7.1%, the price grid is the same.

Prices displayed on 24 September 2026. Price follows the variety more than the percentage: Blood Orange, measured at 11.5%, is displayed at €6.45 per gram in the 2 g pouch, or €2.06 per joint, more than Strawnana at 12.3%. To compare flowers with different percentages, bring the price back to 100 mg of CBD, as in our article on CBD prices in France in 2026, or to the gram of cannabidiol, as for CBD flowers in 100 g pouches. The varieties are grouped in the CBD flowers category; a new batch may show a different percentage.