Liquid ounces vs. weight ounces
 

So liquids and gels individually less than "3 ounces" are allowed. I assume that this refers to liquid ounces.

What about those products that are sold/labeled by weight ounces? Toothpaste & deodorant both come to mind.

Or is an ounce an ounce, that distinction being lost on the average TSA'er?

That occured to me also, but the 3 oz means gel (toothpaste, deodorant) as well as liquid items.

SHHHHH! Don't confuse them!!!!

On ounce of water should be the same for weight and volume (if I remember my schooling). For liquids/gels more dense that water, 1 fl oz, will weigh more than 1 ounce.
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13F

When I came chackpoint at PHX yesterday and when TSA screener told me that she took my toothpaste because it is too big more than 3 oz. So I didn't want to do it for me when I am taking the toothpaste into the checkpoint. When I pull out from my bag and show her something to her. I can have allowed beyond checkpoint with the eye drop is okay for me. When I talk with TSA lady when she check the monitor at the x-ray machine and She told me that I have to less than 3oz beyond checkpint and I will do that next time when I am traveling out from PHX. Where I should need buy with the toothpaste for least 3oz at Walgreens or something other good stores in PHX. Thanks!

What? :confused:

Yes Walgreens or similar places have a "trial size" section where small (less than 1 oz) of toothpaste would be about a dollar. Deodorant and other stuff of any kind in those sizes from that part of the store are okay, too, in your plastic baggie.

I hope that helps.

He means that the TSA workers would be confused trying to understand the difference between 3 oz of liquid and 3 oz of solid/gel.

"Ounce" technically refers to an avoirdupois (weight) ounce; "fluid ounce" is the proper term to connote a volume measurement.

Perhaps the TSA decided to keep things simple, and its usage of the ambiguous "ounce" means that its intent was to allow passengers to carry through checkpoints any toiletry having a weight of 3 ounces or less or having a volume of 3 fluid ounces or less.

Perhaps the TSA was unaware of the distinction above and intended "ounce" to mean "fluid ounce." Any conflict resulting from the difference between fluid ounces and avoirdupois ounces arguably should be resolved against the rulemaker, meaning that passengers should be allowed to carry through the checkpoint toiletries weighing 3 ounces and toiletries having the volume of 3 fluid ounces. (Good luck arguing this point to any ziptop martinet you may encounter.) Besides, would the specific gravities of most liquid or gel toiletries weighing 3 ounces have any significant variances exceeding 3 fluid ounces? I say, "No!"

I have this one container of shaving gel thats labeled Net wt. 2.75 oz. The size of the container would indicate more than 3 fluid oz.

A loophole in your favor. :)

You got me thinking -- I think the relationship is in the metric system. If I remember correctly, 1ml of water weighs 1mg.

Can someone please explain to me why 3 ozs or less a safe number? :confused:

I imagine the TSA surveyed and found that the smallest commercially produced containers of widely used toiletries, cosmetics etc are 3 ounces or less. Simplicity is important, it would be unwieldy to have a separate size limitation for each commodity. The quart bag restriction still creates an incentive to carry the smallest size one can find.

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1 mL of water = 1 gram.

Speaking of confusing the TSA, I wonder what they would do if confronted with stuff that is only labeled in metric units.

I have a bunch of stuff from a trip to Asia that is labeled in metric units only. I wonder how they are going to react to my 70ml bottles of shampoo, 9 gram tube of toothpaste, and 85 gram stick of gel deodorant. Something tells me they won't have any idea if they are 3 oz or less (all of them are though).

that would be 1 gram.. but a liquid with higher density would be heavier.

while 1 ml of mercury would be about 13.5 grams.

http://en.wikipedia.org/wiki/Mercury_(element)

From my experience so far with the latest idiocy, they only care what the label on the container says.

I've been wondering what happens if you show up at a checkpoint with a large container of something that is, say, 13oz but where the leading "1" has been removed. My guess is that it'll sail right through.

They took a good long hard look at a bottle of ink that I had that was labeled only in metric. Then they let it through. 50 mL.

Thanks!! I will have explain something about toothpaste beyond the checkpoint. I will bring less 3oz next time when I am fly out from PHX.

FWIW there are about 28.3 grams (mL) to an ounce.

I just stopped by an McDonald's and saw a box of McFlurry mix outside. It was labeled in liquid ounces, so liquid ounces it is.