TSA Liquids Rule: 3.4 oz, the Quart Bag and the Exceptions

The rule in one line

3-1-1

containers of 3.4 oz (100 ml) or less · 1 quart-size bag · 1 bag per passenger

TSA allows a quart-size bag of liquids, aerosols, gels, creams and pastes in your carry-on and through the checkpoint. Each item must be in a travel-size container of 3.4 ounces or 100 milliliters or less, and each passenger is limited to one such bag. TSA notes that putting these items in the bag and keeping it separate from the rest of your carry-on makes screening easier. Anything that sets off an alarm gets additional screening, and on any item the TSA officer has the final word.

What counts as a liquid

More than drinks. The rule covers liquids, aerosols, gels, creams and pastes, and TSA names the usual suspects: toothpaste, shampoo, conditioner, mouthwash and lotion. It is the form that counts, not the purpose: hair spray, for example, is an aerosol, and TSA allows it in carry-on bags only up to 3.4 ounces or 100 ml.

The limit applies to the container, not to what is left in it. TSA says to pack items in containers larger than 3.4 ounces or 100 milliliters in checked baggage, so a large bottle that is nearly empty still does not pass. Decant into travel-size bottles instead.

Bottle sizes in ounces and milliliters

A US fluid ounce is 29.57353 milliliters, so 3.4 fluid ounces is 100.6 ml and 100 ml is 3.38 fluid ounces. TSA treats them as the same limit, which is why both appear on its page. The tables convert the common sizes and show whether the container is within the limit.

Bottle (fl oz)	In ml	Carry-on?
1 oz	29.6 ml	Yes
2 oz	59.1 ml	Yes
3 oz	88.7 ml	Yes
3.4 oz	100.6 ml	Yes
4 oz	118.3 ml	No, check it
5 oz	147.9 ml	No, check it
6 oz	177.4 ml	No, check it
8 oz	236.6 ml	No, check it
12 oz	354.9 ml	No, check it
16 oz	473.2 ml	No, check it

Bottle (ml)	In fl oz	Carry-on?
15 ml	0.51 oz	Yes
30 ml	1.01 oz	Yes
50 ml	1.69 oz	Yes
75 ml	2.54 oz	Yes
100 ml	3.38 oz	Yes
125 ml	4.23 oz	No, check it
150 ml	5.07 oz	No, check it
200 ml	6.76 oz	No, check it
250 ml	8.45 oz	No, check it
500 ml	16.91 oz	No, check it

For other units, such as a tablespoon of face cream or a liter of shampoo, the volume converter does the conversion.

The quart-size bag

A US liquid quart is 32 fluid ounces, or 946 ml. TSA's pages ask for a quart-sized bag and give no dimensions. On paper a quart holds 9 full 100 ml containers; in practice bottles are not shaped to fill a bag, so plan on fewer and make sure the bag still closes. The limit is one bag per passenger, so each traveler in a group packs their own.

Worked example: a weekend kit

Take the five items TSA itself names as examples, in common travel sizes:

Item	Size	In ml
Shampoo	3 oz	88.7 ml
Conditioner	3 oz	88.7 ml
Toothpaste	3.4 oz	100.6 ml
Mouthwash	3 oz	88.7 ml
Lotion	2 oz	59.1 ml
Total	14.4 oz	426 ml

Every container is within the limit, and together they hold 426 ml, about 45 percent of the volume of a quart. That leaves volume to spare on paper; whether the bottles fit with the bag closed depends on their shape. Swap the 3 oz shampoo for a 4 oz bottle and the kit no longer passes, even though it adds only 29.6 ml: the 4 oz container is over the limit by itself.

The exceptions

Medically necessary liquids and some items for infants are exempt in reasonable quantities; see the TSA liquids page for what qualifies.

The second exception is for duty-free purchases on the way into the United States. Liquids over 3.4 ounces may stay in your carry-on if all three conditions hold:

You bought them abroad and are flying to the US with a connecting flight.
The shop packed them in a transparent, secure, tamper-evident bag that shows no sign of tampering.
You have the original receipt, and the purchase was made within 48 hours, so a bottle bought 2 days before the connecting flight is at the edge of the window.

The sealed items are still screened, and anything that alarms or cannot be screened is not allowed in the cabin. TSA recommends checking such liquids anyway, and liquids over the limit outside a sealed bag must go in checked baggage.

Checked bags have different limits

The 3.4 ounce rule is a checkpoint rule; TSA sends larger containers to checked baggage. Some toiletries are limited there too: TSA notes that the FAA limits the total amount of restricted medicinal and toiletry articles, including aerosols, in checked bags. The FAA's list for this group includes aerosols, hair spray, perfume, shaving cream and sunscreen. For these articles, no single container may exceed 500 ml (17 fluid ounces) or 0.5 kg (18 ounces), and the total per person may not exceed 2 liters (68 fluid ounces) or 2 kg (70 ounces). That is room for 4 full 500 ml containers. Aerosol nozzles must be protected by a cap so they cannot go off in the bag.

Carry-on or checked: the summary

What you pack	Carry-on	Checked bag
Containers of 3.4 oz (100 ml) or less	Yes, in the one quart-size bag	Yes
Containers over 3.4 oz	No	Yes; restricted toiletries up to 500 ml each, 2 L in total
Duty-free liquids, sealed bag and receipt, US-bound connection	Yes, if they clear screening	Yes, and TSA recommends it
Medically necessary liquids, some infant items	Exempt in reasonable quantities	See the TSA page

Packing it

Fill the quart bag last, after the rest of the carry-on is packed, and keep it on top.
Anything over 3.4 ounces, or that does not fit in the bag, goes in the checked suitcase.
The packing list generator builds a list from the trip length and weather, and the printable packing list is a ready-made checklist.

The liquids rule sits next to the ID rule at the same checkpoint; REAL ID explained covers which IDs TSA accepts.

Frequently asked questions

What is the TSA liquids rule?

In carry-on bags, liquids, aerosols, gels, creams and pastes must be in containers of 3.4 ounces (100 milliliters) or less, and all of them must fit in one quart-size bag per passenger. TSA calls it the 3-1-1 rule. Anything in a bigger container goes in checked baggage.

Is a 100 ml bottle allowed if the rule says 3.4 ounces?

Yes. TSA states the limit as 3.4 ounces or 100 milliliters, so a bottle labeled 100 ml is within it. The two are not exactly equal: 100 ml is 3.38 US fluid ounces and 3.4 fluid ounces is 100.55 ml, but TSA uses them as the same limit.

Can I bring a half-empty large bottle?

The rule is about the container. TSA says items in containers larger than 3.4 ounces or 100 milliliters must be packed in checked baggage, so a large bottle with a little shampoo left in it does not qualify. Decant it into a travel-size container instead.

Does the liquids rule apply to checked bags?

No, the 3.4 ounce limit is a carry-on rule. In checked bags, the FAA limits restricted toiletries such as aerosols, hair spray and perfume: no container over 500 ml (17 fluid ounces), no more than 2 liters (68 fluid ounces) in total per person, and aerosol nozzles must be capped.

Are there exceptions?

Medically necessary liquids and some items for infants are exempt in reasonable quantities; the TSA liquids page lists the categories. Duty-free liquids bought abroad on the way to a US connection can also be larger if they stay in the sealed bag from the shop with the receipt.

Sources

Written by Tobias. Updated October 26, 2026.