If you’ve been dreaming of toting a suitcase full of shampoo, body wash and toothpaste on your next vacation, you’re in luck: You can pack as many full-size toiletries into your checked bags as you want. But if you’re packing toiletries in your carry-on bag, you must abide by the Transportation Security Administration’s 3-1-1 rule, which limits the amount of liquids, gels, creams, pastes and aerosols that you can carry onto the flight with you.

Decoding the 3-1-1 Rule

The TSA’s 3-1-1 rule caps the size of any liquids, gels, creams, pastes or aerosols that you carry on at just over 3 ounces: 3.4 ounces or 100 milliliters for each container, to be exact. You can take as many of those small bottles as will fit into a 1-quart zip-lock bag, although you should be able to zip the bag closed – so don’t cram it completely full.

Allowable Toiletries

If you’re into removing nose hair with dynamite, sorry; you’re out of luck. But any reasonable toiletries can go on the plane with you as long as they follow the 3-1-1 rule. These include aerosols like hairspray, deodorant and mousse; shampoo and conditioner; shower gel or body wash; toothpaste; and miscellaneous cosmetics, creams and moisturizers.

Medically Necessary Extras

The TSA also allows you to take reasonable quantities of medically necessary liquids, gels and aerosols – which includes contact lenses and contact lens fluid – through separately from your quart-size baggie, but you must declare those items when you go through the security screening checkpoint.

Unsurprisingly, plenty of traveler anecdotes are out there about variable handling of this rule. If any of your toiletries really are medically necessary in a quantity that won’t fit in your “3-1-1” quart-size baggie, you can smooth the way by keeping them in their original packing and bringing a copy of your prescription or a doctor’s note of medical necessity. Some travelers also print out a copy of the TSA’s own policy to show as proof – just in case.

Consider Hard Toiletries

If you want to pack more than a quart-size baggie’s worth of toiletries in your carry-on, consider packing hard – that is, non-liquid – toiletries. Examples include deodorant bars, bar shampoo and bars of soap instead of body wash. You can even pack tooth powder instead of toothpaste, and if your skin isn’t too finicky, you can substitute lotion bars for a liquid moisturizing lotion.

Tip

Even if you can't pack quite as many toiletries as you want or you need a refill on the road, you can almost always find what you need at your destination. If you're traveling outside the United States and don't have access to travel-size hotel toiletries, you can usually find travel-size toiletries stocked in larger pharmacies.