Travel Tips

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What Does 100 ml Look Like? (Details of TSA's 3-1-1 Rule)

Understand TSA's 3-1-1 Rule for carry-on liquids. Learn what 100ml looks like & tips for packing toiletries within limits for hassle-free travel.

Tobi Miles
September 6, 2022
What Does 100 ml Look Like? (Details of TSA's 3-1-1 Rule)

Anyone familiar with modern-day air travel is familiar with the preflight screenings performed at security checkpoints. The Transportation Security Administration (TSA) agents scan you with wands and send your carry-on bags through the X-Ray machine. Often, they'll scan your toiletry items separately to ensure the containers are 100 ml, but what does 100 ml look like?

Liquid measures allowed inside the plane's cabinet must meet the TSA 3-1-1 Rule requirements. The TSA allows containers of 3.4 ounces or less–or 100 milliliters–of liquids in your carry-on bag. This measures a little over ⅓ cup or 64 tablespoons. 100 milliliters can look like ⅓ the size of an aluminum soft drink can.

This rule sets the number of liquid travel-sized items you can bring onto the plane with you. These regulations were introduced in 2006 to maintain airport and flight safety. So when you’re packing for your next flight, make sure to know the rules for any liquids you plan to bring.

What Is The TSA's 3-1-1 Liquids Rule?

The TSA 3-1-1 Liquids Rule governs how much liquid is allowed inside a carry-on bag on a plane. Liquids, gels, and aerosols must be a maximum of 3 ounces–3.4 specifically, or 100 milliliters–to pass the TSA checkpoint.

Each passenger can bring one 1-quart-sized bag containing the approved 3-ounce containers. You must stow any liquid item measuring more than 100 milliliters in your checked luggage. Otherwise, it won't be allowed, and you will need to throw it away at the TSA checkpoint.

The liquids bag should be easy to open and close, as well as close fully to seal in and hold the bag's contents. It should also be easily accessible for screening at the TSA checkpoint. Being leakproof and airtight are added bonuses, as this will protect the rest of your belongings.

How Much Liquid Is 100 ml?

100 milliliters measures exactly 3.3814 ounces or 3.4 ounces for convenience. 3.4 ounces equals a little more than ⅓ of a cup or 64 tablespoons. For comparison, two standard well shots are nearly the same amount of liquid as the TSA check-in limits.

Related Read: How Big Can My Toiletry Bag Be To Fly? Quart-Size Bags

Is 100 ml Travel Size?

Typically, most travel bottles or travel-sized products hold 3 fluid ounces of product. Since 100 milliliters converts to 3.4 ounces, travel size is slightly less than 100 milliliters. In fact, 3 fluid ounces of liquid is equal to 84 milliliters, which is 16 milliliters short of the limit.

Some containers can be smaller or larger than 3 ounces. This will change the amount of milliliters these containers will hold. You will have to ensure that your items don't exceed the TSA limits.

Is 100 ml The Same As One Cup?

No, 100 milliliters is a bit less than a full cup. It's slightly more than ⅓ cup at 3.4 fluid ounces. That's a little more than a generous tequila shot and very close to a three-finger glass of aged whiskey.

Why Can You Only Have 100 ml On A Plane?

The TSA liquid limit regulations came about as a result of a failed terrorist plot in 2006 at an airport in Britain. The police discovered powdered Tang beverage mix and an unusual number of batteries in inspected baggage, which alerted suspicion.

Further investigation revealed a plot to blow up seven planes heading to North America using drink bottles as explosives. As a result, airports began putting restrictions on liquid within passenger baggage.

Since X-Ray technology has trouble determining a liquid's volatility, controlling the amount of liquid seemed a safe, effective option. The authorities surmised the lower amount of liquid would pose less of a threat if a dangerous substance slipped past the security check.

The TSA 3-1-1 limit does have some concessions, such as prescription drugs, life support and life-sustaining liquids, and baby formula. These items are still subject to scanning and sometimes tasting at the TSA baggage check.

Tech development in computed tomography (CT) machines has improved detection capabilities. Many airports are relaxing these restrictions in light of these innovations.

Related Read: How to Choose an 18x 14x8 Bag

How Many 100 ml Bottles Can You Bring On A Plane?

You can comfortably fit about 5 or 6 items inside a one quart-size plastic bag without overstuffing it. That equals 15 to 18 ounces total you can bring into the cabin. Additionally, you can fit other toiletry items in the quart bag, such as a disposable razor, small comb, or toothbrush.

Most travel bottles and prepackaged "travel-sized" items sell in 3-ounce containers. Some manufactured products may be more than 3.4 ounces. It's a good idea to check the labels and confirm how much each container holds before packing.

Do Liquids Show Up On X-Ray?

Liquids do show up in an X-Ray scan. However, the technology is not advanced enough to screen whether or not it is potentially dangerous.

It may be subject to more thorough inspection and testing. Because of this, the X-Ray machine's limitations could cause extensive delays, or false judgment calls on questionable liquid items.

Fortunately, scientists and engineers are developing and improving CT scanners. These scanners can more accurately determine a liquid's volatility before passing inspection. Implementing these new technologies will relax the liquids ban and eventually dismiss it altogether.

Related Read: How Many Fluid Ounces Can You Carry On A Plane?

Will The TSA Measure Liquids?

Currently, the TSA uses an X-ray with an alarm to measure liquids. The TSA screens for liquids through X-Ray.

An alarm on the machine will trigger at more than 3.4 ounces, pulling a liquid for further screening. Visual inspection can also flag an item for more thorough checking.

Will The TSA Test Liquids?

Any liquid that registers above the fluid limit or raises concern with the TSA agents may be pulled aside for further screening. Some exception items like baby formula and breast milk may also be screened and tested separately. The TSA has different solutions and things they can use to test various liquids.

Are There Any Exceptions to the 3-1-1 Liquids Rule?

There are some exceptions to the liquids rule, and they all pertain to dependent or urgent medical care. Prescription and liquid medications are some of the exceptions, provided they are packaged in their original bottle and properly labeled. Additionally, life support and life-sustaining liquids such as nitroglycerin and insulin have similar exceptions.

Baby food, baby formula, and pre-bottled breast milk are notable exceptions, as babies cannot care for themselves. For this reason, the liquids limit is more relaxed on these items. These may be further inspected or require tasting, depending on the circumstances.

Due to the pandemic, you can bring up to 12 ounces of hand sanitizer onto a plane. Furthermore, you are not required to put travel-sized bottles of hand sanitizer inside your liquids bag.

Related Read: How Strict Is Alaska Airlines With A Carry-On?

How Much Liquid Can You Take On A Plane In Checked Baggage?

There is no real limit on how much liquid you can have in your checked luggage, with the exception of hard liquor. Hard liquor between 24 and 70 percent alcohol content is limited to 5 liters per checked bag.

Alcohol above 70 percent alcohol content is banned on flights traveling within the United States. Alcohol limits for international travel vary between individual countries.

With that said, you'll want to guard against breaking or leaking when packing your liquid items. Seal items in a leakproof bag to prevent staining clothes or your suitcase interior. If the container is breakable, wrapping it in a few layers of clothes will help insulate it from any bumps to the luggage.

How Much Liquid Can You Bring On International Flights?

Liquid limits on international flights may vary depending on the country you're traveling to or from. Generally, though, you can carry as much liquid as you can safely secure in your suitcases.

You'll find that many of the limitations for liquids on domestic flights will also apply to international flights. However, depending on the type of liquid, there may be further regulations and packaging requirements.

Alcohol, particularly duty-free alcohol, has a different set of shipping standards. These need to be packed by the retailer in secure, tamper-evident, transparent bags. In addition, travelers need an original receipt as proof of international purchase made within 48 hours of the scheduled flight.

What Is the Best Way To Pack Liquids In Your Carry-On?

Nalgene bottles are highly recommended due to their shatterproof and leakproof properties. You can also purchase refillable bottles and fill them with the items you use at home. Check the package size of any retail items dubbed "travel size" to ensure they meet TSA standards.

All of these items must fit comfortably inside a clear quart-size bag and be able to open and close easily. Make sure each item is easily visible. Pack this clear pouch toward the top of your carry-on bag to save time at the screening checkpoint.

When preparing to pack liquids in your carry-on, first prioritize what items you plan to bring. Items like soap and solid deodorant can go directly into your carry-on. The more liquid items you can substitute, the more convenience items you can pack.


The 3-1-1 Rule allows as many 3.4-ounce containers of liquid that will fit in 1 quart-size bag for carry-on for every single passenger. The bag must be transparent and able to open and close with ease.

The liquids bag is separate from the main carry-on bag so that the TSA agents can quickly inspect them for safety. Any liquids above the 3.4-ounce limit must be stowed in the passenger's checked luggage or discarded at the security checkpoint.

Certain exceptions, like baby needs or prescription, over-the-counter, and life-sustaining medications, do not have the same limits but are subject to inspection. Duty-free items are allowed for carry-on in transparent, tamper-evident bags sealed by the seller.

Air travel is stressful enough without taking the TSA 3-1-1 Rules into consideration. However, knowing what is and isn't allowed beforehand and how and what to pack can save you many headaches and hassles. So, it's worth knowing the rules and taking the proper steps beforehand, so your travel plans go as smoothly as possible.

Tobi Miles
Article updated:
March 28, 2024
A nomadic wordsmith savoring the world's flavors and penning stories that turn every journey into an epic.
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