It says on the TSA website that all 3 oz. liquids must be in a quart size baggie, not a little fold over sandwich baggie and not a gallon size baggie.

You can technically bring a gallon-sized Ziploc bag through TSA in 2026, but you cannot use it to hold your liquids if you want to follow the 3-1-1 rule. The TSA's liquid regulations strictly require that your 3.4oz (100ml) containers must fit into a one-quart-sized (approx. 1 liter) clear, resealable bag. A gallon bag is significantly larger (4 quarts) and will likely be flagged by security, leading to a manual search or the potential confiscation of your items if they don't fit into a standard quart bag provided at the checkpoint. However, you can use gallon bags for non-liquid items, such as organizing your socks, protecting your electronics from moisture, or keeping snacks fresh. If you have "medically necessary" liquids or breast milk, these are exempt from the quart-size limit and can be carried in larger bags, but you must declare them to the officer for separate inspection. For standard toiletries, stick to the quart-sized bag to ensure a smooth transition through the X-ray machine.