The travel limit for deodorant depends entirely on its physical form. If you are using a solid stick or powder deodorant, there is no size limit for domestic or international carry-on luggage; you can bring a full-sized stick without any issues. However, if your deodorant is a liquid, gel, or aerosol spray, it must comply with the global "3-1-1" rule for liquids. This means the container must be 3.4 ounces (100ml) or less, and it must fit inside your single, quart-sized, clear plastic zip-top bag. If you try to bring a standard 5 oz aerosol spray through security, it will be confiscated, even if the can is nearly empty. It is a common mistake for travelers to think "gels" don't count as liquids, but for security purposes, anything that can be poured, smeared, or sprayed falls under the liquid restriction. If you absolutely need a large aerosol or a high-volume liquid roll-on, you must pack it in your checked luggage, where there are much more generous limits (usually up to 18 oz per container for medicinal or toiletry aerosols, not exceeding 70 oz total).