How big suitcase can I take on the plane when traveling abroad? The suitcase I bought is 29 inches. Can I take it? (Three people use this suitcase together)

The size of the carry-on suitcase is very small, so the space for three people is definitely not enough, so luggage can only be checked:

A suitcase that can be carried on the plane is called a boarding box, which generally requires that the sum of three sides should not exceed 115cm (that is, the sum of length, width and height should not exceed 115cm) and the weight should not exceed 7kg.

About checked baggage:

The free checked baggage allowance for economy class passengers is 2kg;

For economy class passengers with student passports, the free checked baggage allowance is 3kg;

the free checked baggage allowance in business class is 3kg;

the free checked baggage allowance for first class is 4kg.

however, when the destination is America, the checked baggage can be two pieces, each of which does not exceed 23kg, and the sum of the three sides of a single piece of luggage does not exceed 158cm. When it is exceeded, passengers need to pay the excess baggage fee. Note: As different airlines have different requirements, passengers can consult the airlines they will take in advance.