The cabin liquids rule sets the bottle size and the bag size both
Most airport security regimes, closely following a widely adopted international standard, limit cabin liquids to containers of 100 ml or less, all carried together in a single transparent, resealable bag of roughly one liter — a bottle sized at 100 ml but carried in an opaque or oversized bag can still be flagged at the checkpoint. We compare refillable bottle sizing and leak-proof cap design, and liquid bag compliance with that common size and transparency standard, while noting explicitly that exact rules vary by country and are always worth confirming before traveling.
A transparent, resealable one-liter bag sized to the widely used cabin liquids standard, sold in a multi-pack for repeated use.
Containers are limited in individual volume and must fit in a resealable transparent pouch of imposed dimensions. Those rules do not depend on the airline.
It is the volume marked on the container that counts, even if it is half empty. A large, barely filled bottle is refused.
The pressure difference pushes the contents outward. Never fill to the brim and close firmly.
With a small funnel or a syringe for fluid products. Pouring directly runs onto the threads, which then no longer seal.
Yes, after washing and drying completely. A badly dried bottle contaminates the next product.
Solid shampoos and toothpastes escape the rules on liquids. An increasingly used solution.
Identical bottles are easily confused. A label or a cap color avoids mistakes.
No: leaving a little air lets the bottle absorb the pressure change without straining the cap. A bottle filled to the brim is the first one to leak.
It is the volume marked on the container that counts, not what is left inside: a large half-empty bottle is refused. Never fill to the brim — the pressure in flight makes it overflow — and solid products escape these rules entirely.