The TSA 3-1-1 rule means each traveler may bring liquids, gels, aerosols, creams, and pastes in containers of 3.4 ounces or 100 milliliters or less, and all of them must fit inside one quart-size bag. That bag goes in your carry-on and gets screened at the checkpoint.
The rule is why toothpaste, shampoo, lotion, and similar items have to be packed in travel sizes. If the container is larger than 3.4 ounces, TSA treats it as too big even if there is not much product left inside.
So the easy way to remember it is 3 ounces per container, 1 quart-size bag, 1 bag per passenger. The official number is 3.4 ounces, but the shorthand gets people through security without guessing.
Want the full picture?
🧊 Solo Travel and Pet Travel — The Two Trends Reshaping How We Move
Traveling alone and traveling with pets are exploding in 2026 — driven by new airline routes, AI planning tools, and a cultural shift toward experiences that fit your actual life instead of a brochure.
More in Travel
Do I need travel insurance?
You need it if you're traveling internationally where your health insurance doesn't apply, or if you've prepaid non-refundable costs you can't afford to lose.
✈️ Travel 13 weeks ago 2 min readHow can I get through airport security faster?
PreCheck, organized carry-ons, and simple clothing choices usually save the most time.
✈️ Travel 11 weeks ago 2 min readHow do I avoid jet lag on long flights?
Shift your sleep and light exposure toward the destination before you fly, stay hydrated, and avoid landing exhausted; melatonin can help shift the clock for eastbound trips.
✈️ Travel 8 weeks ago 3 min read