With a medical card, you can typically possess between 1 and 8 ounces of dried cannabis flower at a time, though the exact ceiling is set by your state and a handful of states go much higher. Oregon tops the list at 24 ounces of usable cannabis, and Massachusetts frames its 10-ounce limit as a 60-day supply. Forty states, three U.S. territories, and the District of Columbia run medical cannabis programs, and no two set identical rules on how much you can buy, hold, or grow.1National Conference of State Legislatures (NCSL). State Medical Cannabis Laws
How Much You Can Possess
Possession limits govern the total amount you can legally have on you or stored at home at any given moment. Most state programs land somewhere between 2 and 8 ounces of dried flower.
On the low end, Alaska and Montana cap medical patients at 1 ounce. Colorado, Michigan, and Maine sit in the middle at roughly 2 to 2.5 ounces. Hawaii and Florida allow 4 ounces, Delaware permits 6 ounces, and Washington, D.C. allows 8. Oklahoma splits its rule by location: up to 3 ounces on your person and 8 ounces kept at home. Oregon’s 24 ounces and Massachusetts’s 10-ounce, 60-day supply are the clearest outliers.
A few states also let a physician certify that a patient needs more than the standard cap. California sets its baseline at 8 ounces but permits a doctor to recommend a higher amount for someone with a qualifying severe condition. If you have a heavy medical need, ask your certifying physician whether your state offers this kind of exception.
How Much You Can Buy at a Time
Possession is what you can hold. Purchase limits are a separate rule: they cap how much you can buy from a dispensary over a defined window, most commonly 30, 60, or 90 days. Your state’s monitoring system tracks every purchase against that rolling allotment, and every licensed dispensary reports into it. Visiting a second dispensary won’t get you around the cap.
A 30-day supply is the most common framework, but what it translates to in grams or ounces isn’t uniform. In some states a 30-day supply is 2.5 ounces of flower; in others, closer to 4. The number also shifts by product type, because flower, concentrates, and edibles each get their own count. Your state health department’s page or the budtender at your dispensary can give you the specific figures tied to your card.
How Concentrates and Edibles Count Against Your Limit
Cannabis comes in many forms, and each state converts them back to a single yardstick, almost always ounces of dried flower. That’s what makes the math trickier than it looks.
Concentrates are consistently treated as much more potent than flower. Rhode Island, for example, treats 7.7 grams of concentrate as the equivalent of 1 ounce of flower, so a single gram of concentrate counts as roughly 3.7 grams against your allotment.2Legal Information Institute (LII). Rhode Island Code 216-RICR-20-10-3.13 – Equivalency and Conversion Amounts Edibles are usually counted in milligrams of THC, with a set number of milligrams standing in for an ounce of flower.
The practical result: mixing product types burns through your allotment faster than the raw weight suggests. If you buy an eighth of concentrate along with your flower, the dispensary system converts everything to flower-equivalent before checking your total. The register handles the math automatically, but knowing how it works helps you plan a purchase without hitting a wall.
Growing Your Own
Not every medical state lets you grow. Where it’s allowed, the rule is usually a fixed number of mature (flowering) and immature (vegetative) plants, with common household limits between 4 and 12.
The range in practice: Illinois allows medical patients up to 5 plants. Maine permits 3 mature and 12 immature. Vermont caps it at 2 mature or 4 immature. Michigan allows up to 12 plants per household. Some states set both a per-patient and a per-household maximum, so two cardholders under one roof each grow their individual allotment only up to the shared household cap. Most states that permit home cultivation also require the grow to be in an enclosed, locked space that isn’t visible or accessible to the public.
If you grow, watch your total holdings carefully. Combining a harvest with recent dispensary purchases is one of the most common ways patients accidentally cross their possession limit.
Why a Medical Card Still Beats Recreational
In states with both medical and recreational cannabis, holding a medical card almost always lets you possess more. A review of dual-program states found medical limits exceed recreational limits in every one except Michigan, where the two are equal.3National Center for Biotechnology Information. State Variation in U.S. Medical Cannabis Limits, Restrictions, and Access The gap is sometimes sharp: a recreational user capped at 1 ounce, a patient in the same state allowed 2.5 or more.
Cardholders often get other advantages too: lower or waived taxes, access to higher-potency products, the right to grow at home where recreational users can’t, and dispensary access in areas that don’t license recreational shops. These are the reasons many patients keep renewing their cards after their state legalizes for adult use.
What Happens If You Go Over
Exceeding your possession or purchase limit removes your card’s legal protection for the excess amount. What’s left is possession of cannabis beyond an authorized quantity, which most states treat as ordinary unlawful possession. Penalties depend on the state and how far over you are: misdemeanor or felony charges, fines, and revocation of your medical card are all on the table. Losing the card usually means you can’t reapply for a set period.
The point-of-sale tracking makes it very hard to blow past a purchase cap by accident. Patients more often run into trouble by accumulating product over time, accepting cannabis from other patients, or letting a home harvest stack on top of recent dispensary buys. Keep a rough running total of what’s actually in the house.
Where Your Card Doesn’t Reach
Your card sets what you can hold inside your state. It doesn’t cover several situations patients often assume it does.
Airports and State Lines
Cannabis remains illegal under federal law, and airports fall under federal jurisdiction. The TSA says its officers “do not search for marijuana or other illegal drugs,” but if cannabis turns up during screening, they’re required to refer the matter to law enforcement.4Transportation Security Administration. Medical Marijuana What follows depends on local police at that airport. Driving cannabis across a state line is also technically a federal offense, even between two states where it’s legal. A small number of states offer reciprocity for out-of-state medical cards, including Nevada, New Jersey (up to six months), Maine, Michigan, and Delaware; large medical states such as California, Florida, and Texas do not. Verify the current rule before you travel.
Firearms
Federal law bars anyone who is “an unlawful user of or addicted to any controlled substance” from possessing, buying, or receiving firearms or ammunition.5Office of the Law Revision Counsel. 18 U.S. Code 922 – Unlawful Acts Cannabis is federally controlled, so every medical cardholder falls in that prohibited category regardless of state law. ATF Form 4473, filled out at any licensed firearms dealer, asks directly whether you use marijuana and warns that it “remains unlawful under Federal law regardless of whether it has been legalized or decriminalized for medicinal or recreational purposes in the state where you reside.”6Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Firearms Transaction Record – ATF Form 4473 Answering “yes” blocks the sale; answering “no” with an active card is a federal felony.
Federally Assisted Housing
If you live in or are applying for Section 8, public housing, or any other federally assisted housing, your card can put your tenancy at risk. Under the Quality Housing and Work Responsibility Act, property owners receiving federal assistance must deny admission to anyone currently using a federally illegal substance. For existing tenants, owners have discretion to evict on a case-by-case basis, and they cannot adopt policies that affirmatively permit marijuana use on the property.7U.S. Department of Housing and Urban Development. Use of Marijuana in Multifamily Assisted Properties Private housing without federal subsidies isn’t governed by these rules, though your lease terms still apply.