The security limit
Updated
On this page8
Why it is a different kind of rule
The hazmat exception exists because a flammable or pressurized article is a transport hazard. The carry-on liquids limit exists for security screening reasons. Different authority, different purpose, and no reason for the numbers to agree.
Which one binds
The smaller one, for a carry-on bottle. A container can satisfy the hazmat ceiling comfortably and still be refused at screening, and that is the outcome a customer experiences rather than the regulatory one.
And checked baggage is a different answer again
The hazmat exception covers checked baggage, and the security liquids restriction is about what goes through a passenger screening checkpoint. A larger bottle in a suitcase is a different question from the same bottle in a backpack.
Why we will not state the number
A figure in a published page outlives the rule it came from. Writing it here would be the kind of stale authority this library is built to avoid, so the reference points at TSA directly.
Design to the smaller limit anyway
A travel range built around containers comfortably under the stricter figure works under both rules and keeps working if either moves. That is the robust design choice rather than optimizing to a current number.
Which is what this shelf does
127 of the 203 containers here are at or under 100 mL, and the whole shelf tops out at 120 mL. So it was built for the tighter constraint rather than the regulatory ceiling.
Airlines add their own conditions
A carrier can be more restrictive than either rule, particularly for aerosols and for anything with alcohol in it. For a product sold to travelers that is worth a line in the copy.