Cabin bag rules can be confusing, but the guidance on Delta Carry On Size Liquids is simple once you know it. Every container must be small enough to qualify as travel-size, and all of them must fit inside one clear, resealable bag. Officers look at the container itself, not how full it is. Medications and baby formula are the main exceptions, and they should be declared at the checkpoint. Any larger container belongs in checked baggage, which helps you avoid delays and repacking.