What is the 3-1-1 rule?
The 3-1-1 rule is the TSA limit on liquids in carry-on bags. Each passenger may bring liquids, gels, aerosols, creams and pastes in containers of 3.4 ounces (100 milliliters) or less, all packed inside one clear quart-size bag. Each traveler is allowed one such bag through the security checkpoint.
The rule applies at every Transportation Security Administration (TSA) checkpoint in the United States, from the small terminal at St. George Regional Airport (SGU) to Las Vegas Harry Reid International and Salt Lake City International. It covers your carry-on bag and your personal item. It does not apply to checked luggage.
What does 3-1-1 stand for?
Each number in the name stands for one part of the rule:
- 3 — every container must hold 3.4 ounces (100 ml) or less. The limit is the size printed on the container, not how much is left inside it.
- 1 — all of those containers must fit in one clear, quart-size, resealable bag (roughly a 1-quart zip-top bag) that closes completely.
- 1 — each passenger gets one quart bag. Families can bring one bag per person, including children.
What counts as a liquid under the rule?
TSA applies the rule to liquids, aerosols, gels, creams and pastes. If you can spill it, spray it, spread it, pump it or pour it, treat it as a liquid. Common examples:
- Toiletries: shampoo, conditioner, body wash, liquid soap, mouthwash
- Gels and pastes: toothpaste, hair gel, styling paste, gel deodorant
- Creams and lotions: sunscreen, moisturizer, face cream, liquid or cream makeup, mascara
- Aerosols and sprays: dry shampoo, hairspray, spray deodorant, perfume and cologne
- Food and drinks: bottled water, coffee, soda, soup, salsa, yogurt, dips, and spreads such as peanut butter or jam
Solid items such as bar soap, stick deodorant, solid shampoo bars and powder makeup are not liquids, so they can travel loose in your bag. TSA officers make the final call at the checkpoint, so if an item seems borderline, put it in the quart bag or pack it in checked luggage.
What items are exempt from the 3-1-1 rule?
TSA makes exceptions for liquids that are medically necessary or meant for infants and young children. You can bring these in amounts over 3.4 ounces, and they do not need to go in your quart bag:
- Liquid medications and medically necessary liquids, gels and aerosols, in reasonable quantities for your trip. Declare them to the officer at the start of screening so they can be inspected.
- Baby formula, breast milk, toddler drinks and baby or toddler food, including puree pouches. Tell the officer you have them and remove them from your carry-on for separate screening.
- Ice packs, freezer packs and gel packs used to keep breast milk, formula or baby food cold are allowed in carry-ons.
- Duty-free liquids bought abroad can be larger than 3.4 ounces if they stay in the transparent, tamper-evident bag from the store and were purchased within the last 48 hours. TSA still recommends packing larger quantities in checked bags.
Exempt items can get extra screening, and TSA says any oversized liquid that alarms may not be allowed through. Contact lens solution is one example: TSA recommends putting bottles over 3.4 ounces in checked baggage. Check the official TSA liquids rule page before you fly for the latest details.
Does the 3-1-1 rule apply to international flights?
Yes, when you depart from a U.S. airport. TSA screens every passenger leaving a U.S. checkpoint, whether the flight goes to Denver or to Europe. On the way home, the airport you depart from sets the rules.
Many countries use a similar 100 ml limit, but the details differ. Some airports abroad have installed newer scanners and relaxed or changed their limits, and some have later reinstated them. Check your departure airport and your airline before you pack for the return flight, and remember that connecting through another country can mean another security screening with its own rules.
Tips for packing under the 3-1-1 rule
- Buy or refill travel-size containers. Reusable silicone bottles labeled 3.4 oz (100 ml) or smaller make it easy to bring your own products.
- Switch to solids. Bar soap, shampoo bars, stick sunscreen and solid deodorant free up room in your quart bag.
- Pack the quart bag last, on top. Put it in an outside pocket or at the top of your carry-on so you can pull it out quickly at the checkpoint.
- Bring an empty water bottle. Fill it after security. This matters in Southern Utah, where dry desert air and summer heat make staying hydrated a priority before and after a flight.
- Check the bag, not the bottle. If you need full-size sunscreen for Zion or a big bottle of lotion, put it in checked luggage or buy it after you land.
- Separate medications and baby items. Keep exempt liquids outside the quart bag in an easy-to-reach spot so you can declare them right away.
Flying into Southern Utah for a park trip? Our St. George visitors guide covers the airport, rental cars and getting to Zion and the other national parks, and the transportation guide lists airport shuttles and ride options.