Curses, I've been caught! I indeed posted my initial query without actually looking at the container (which was all the way at the other end of the house, etc., etc.), not realizing, of course, that an alert FTer would sooner or later notice that the approximations I'd used were in error.

However, 3.5 oz. is not "more than 100 ml," as sailman suggests. That's the whole point, isn't it? 3.5 oz. of something could fill a container significantly larger or smaller than 100 ml - depending on what the stuff is!

In this case, the stuff is toothpaste. The weight is 3.3 oz, and the volume is only 75 ml. If the weight were 3.5 (or 3.6 or 3.7 . . ), the volume would still be significantly less than 100 ml.

By the way, thank you to everyone who suggested just removing the labels and making life easier.

Although, if I didn't actually want to go somewhere, I'd be seriously tempted to take a high school science book to the checkpoint with me.

High school science texts are the terrorist's Bible!

I stick by my initial post. If oz. and ml are used in the same breath without a qualifier for the oz. (volume or wt), the reasonable supposition is that the ounces are in volume as ml (millileters) can be nothing other than a volume measurement.

If you precisely quoted the label, and the ounces are indeed weight rather than volume, then the label is incorrect and in violation of package label laws and guidelines.

One other comment. You need not refer to a high school text. A grade school text will suffice. You don't want to confuse anyone with long sentences with multi-syllable words. After all as our president stated when announcing the "Reading First" initiative in Reston Virginia, March 28, 2000 - "Reading is the basics for all learning." Which is in keeping with the policy of "no child's behind left."

Stay the curse!

Correct. The rule is 3 oz, not 100 mL. http://www.tsa.dhs.gov/311/index.shtm

Except when it's not.... http://www.tsa.dhs.gov/assets/pdf/311-broch-french.pdf

I wonder what would happen if I had a container labeled 1 Newton at ground level since that is the weight of a 3oz mass on the earth's surface

<hides>

Or, take a 50 ml plastic liquor bottle, relabel it in big letters "Net Contents: FIVE US GALLONS" and dare them to confiscate it.

That page is - and has been for some time - wrong. The rule actually is 100mL. The TSA just assumes that everyone in the USA doesn't know what a mL is and tried to convert it to 3 (fl) oz. Of course, that is great for a catchy slogan like 3-1-1, but it is actually not what their policies are written as.

Awesome.

Not so fast my friend.
I bought a travel bottle that did not have a measurement on it. I tested it and it was 3 oz.
The TSA guy questioned it. He let it slide, but I had to explain that I measured it.
It is all so silly.
One 9 oz container = dangerous
3 3oz. containers = perfectly safe

I'm sure these half-wits also use 22/7 for ∏ and then wonder why their hardware doesn't work properly.

I just give them $1.23 when I am charged $.98 after they ring in $1.00 tendered and watch their confused look. Oh wait, that's a different group.....

Be prepared for a huge argument if you try this. The rules don't state that the volume must be on the package, but that doesn't seem to have anything to do with their actual enforcement at some airports. This is true even when it is obvious that the container is smaller than 100ml.

Isn't a Newton related to force and not mass, and equals 3.6 ounce-force?

Stay the curse.

Isn't a Newton related to force and not mass, and equals 3.6 ounce-force? Or is the key "at ground level", assuming earth?

Stay the curse.

Consumers buy milk by volume, but farmers sell it my weight (hundredweight, or 100 lb units).