28 grams
Both residents and non-residents can purchase up to 28 grams in a single transaction. Medical patients may purchase up to 2 ounces of medical marijuana or its equivalent as a standard, though higher amounts may be granted by the recommending physician.
The Colorado law has some grey areas when it comes to defining 'single transaction' so most recreational stores err on the side of caution when selling cannabis, in order to maintain compliance, and will only serve each customer once within a day.
Every state has different cannabis purchase limitations. Sometimes the limit is per day, sometimes during a set period of time, and sometimes it is per transaction. Knowing the purchase limit helps you operate compliantly once licensed for a dispensary and helps with financial planning for your daily dispensary sales.