Montana cannabis purchase and possession limits

One ceiling, three units

The most common misreading of Montana's limit is treating it as three separate allowances. It is one ceiling expressed in three units, and the state converts between them.

For an adult 21 or over, the statute allows 1 ounce or less of usable marijuana. Inside that ounce, no more than 8 grams may be in concentrated form, and no more than 800 milligrams of THC may sit in edible products meant to be eaten or swallowed in solid form.

The Department of Revenue publishes the equivalency it uses: 1 ounce of flower equals 800 milligrams of THC in products, and equals 8 grams or 8 milliliters of concentrate. A mixed basket gets converted at those ratios and counted against the single ceiling.

The math on a mixed purchase

Say you want flower and a cart in the same trip.

Half an ounce of flower uses half the ceiling. That leaves half, which converts to 4 grams of concentrate. Two one gram carts and a gram of live resin fit inside that with room left over.

Now try to add a 100 milligram package of gummies on top of a full ounce of flower. It does not fit, because the ounce already consumed the whole allowance. The register will stop you, and the store's system reports to the state tracking system in real time.

Registered cardholders

Cardholders run against different numbers. State law allows a registered cardholder to purchase up to 1 ounce of usable marijuana per day and no more than 5 ounces per month. The same conversion ratios apply to non-flower products.

A cardholder whose physician confirms that their condition warrants more may petition the Department of Revenue for an exception to the monthly limit. That process runs through the department, not through the dispensary.

The monthly ceiling, not the daily one, is what most cardholders actually hit. It resets on the department's schedule, not on the calendar month you have in your head, so check your remaining balance at the store rather than estimating.

Possession versus purchase

These are separate rules that happen to share a number.

Purchase limits govern what a licensed dispensary may sell you in a transaction. The store enforces them, and a dispensary may not complete a sale that would put you over the personal possession limits set in statute.

Possession limits govern what you may have on you, anywhere in Montana. Buying at the ceiling and then buying again at a second store the same day does not create a legal second ounce. What you are carrying is what counts.

Package limits are a different thing

Montana also caps what a single package may contain, and those numbers get confused with purchase limits.

• Flower: 1 ounce per package, capped at 35 percent total potential psychoactive THC.
• Edible or food product: 100 milligrams of THC per package, with a single serving capped at 5 milligrams as of July 1, 2026.
• Tinctures: 800 milligrams of THC per package.
• Capsules: 100 milligrams per capsule, 800 milligrams per package.
• Topicals: 6 percent THC concentration and 800 milligrams per package.

A package limit describes how a product may be built. A possession limit describes how much of it you may hold. An 800 milligram tincture is a legal package and it consumes your entire edible THC allowance on its own.

Growing and sharing

An adult 21 or over may grow two mature plants and two seedlings at a private residence, kept in a locked space and out of public view. Registered cardholders may grow four and four.

An adult may give up to 1 ounce to another adult 21 or over with no money changing hands. Money changing hands makes it a sale, and unlicensed sales stay illegal.

Carrying what you bought

Montana's transport guidance tells you to keep the product in its unopened original packaging and to carry it in a locked glove compartment, a trunk, a truck bed, or another closed container that a driver or passenger does not normally occupy. Violations carry a civil penalty of up to 100 dollars, and the state's guidance says such a violation does not go on a driver's record or affect insurance rates.

Crossing a state line stays prohibited in every circumstance.

At the counter

The register enforces the ceiling, and a budtender who works around it puts the store's license at risk. If a basket comes back over the limit, the fix is dropping an item, not splitting the transaction.

If you hold a card, present it before the sale rings up so the purchase records against the right limits and the right tax rate. And check these numbers against the Department of Revenue's current pages before you rely on them, because the legislature revisits them every session.