A carry-on and checked verdict for every item, with the reason.
What you can and cannot bring on a plane, one item at a time. Every page gives a carry-on verdict, a checked bag verdict, the quantity or size limit that applies, the reason behind the rule, and how it changes outside the US, all read from TSA, FAA and CBP sources and dated.
Three rules answer most questions. Liquids, gels and aerosols in a carry-on must be 3.4 ounces (100 ml) or less and fit one quart bag, with medication and baby food exempt. Spare lithium batteries and power banks fly only in the cabin, never in the hold. Knives, tools and anything with a blade go in checked baggage. Everything else is a detail, and the details are what the item pages are for.
The officer at the checkpoint has the final say on anything unfamiliar, and airlines add rules of their own on top of the federal ones, so each page also notes what carriers require. Search for an item below, browse by category, or run a whole packing list through the packing list screener.
The rule behind most of these answers
Liquids, gels, creams, pastes and aerosols go through security in containers of 100 ml (3.4 fl oz) or less, all of which must fit inside a single transparent resealable bag of about a quart. It is the size printed on the container that counts, not how much is left in it. Medication, baby formula and breast milk are exempt and are declared separately.