The carry-on limit for TSA is 3.4 ounces but unless you can survive on three products alone it’s pretty dumb. I’m sorry, I’m not Bear Grylls.
Most people have no idea how long their liquids actually last and how it compounds on space in the toiletry bag. They also don’t realize 3.4 ounces (100 mL) is actually pretty damn big.
Let’s think this through one step at a time: The Transportation Security Administration allows travelers to bring as many liquids as they want, as long as it’s contained in a 1 quart bag. The dimensions of that bag can vary, as long the volume capacity is one quart. How they measure this, I don’t know, but I assume we’re all abiding by the honor system here.
I use an “approved” Muji travel pouch—which I frankly assume is the correct size because the Japanese are crazy—which measures 7.7 inches x 6.3 inches (19.5 cm x 16 cm). FlyerTalk user stinky123 notes that a legal Ziploc baggie, the poor man’s pouch, measures 7.5 inches x 8 inches (19.1 cm x 20.3 cm) while FlyerTalk user SLC-YYZ notes TSA proper gave him a bag measured 7.0 inches by 7.5 inches (17.8 cm x 19.1 cm). Looking at all the common measurements, I would say 7.0″ by 7.5″ is probably safe and the median. I’m not going to think too hard on this.
Next, remember that the U.S. commonly uses two different sizes? There’s the actual maximum size, which is 3.4 ounces or 100 mL, or the tourist-remembered size, 3 ounces or 89 mL. Personally, I find it easier to stick to the metric system on this one and remember a flat 100 but yeah, fine, imperial system, whatever. Regardless, what I have at home is a bunch of 3-ounce (89 mL) bottles, so that’s what we’re going to dump into the clear bag.
Using the Muji bag, I can safely fit six bottles into the bag, seven if I tried really, really hard. So for six bottles, that’s roughly 534 to 623 mL of liquid I can squeeze into it. That means if I was using 3.4-ounce bottles, which is the real maximum, you’d be able to get five or six bottles into it… if you manage to contort the bottles into different varying positions and shapes. I don’t know about you but I use well over five types of liquid products. You might be able to squeeze more into a Ziploc bag but I doubt there’s huge give.
Keep in mind most people actually probably don’t even need to bring along 3 ounces of shampoo unless they’re going for weeks and weeks (emphasis on the plural). So 3.4 ounces? Pretty dumb for the most part, unless you only need five products for life.
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