For a trip that includes one or more connections, United will check bags to the final destination stated on the ticket. Usually luggage will be stored on the same flight as the traveler but that't not always the case. You'll need to claim and re-check baggage if you are: Making a voluntary stopover Making a connection that involves an overnight stay Connecting to an itinerary booked on a separate ticket that doesn't include a Star Alliance partner airline Traveling internationally and connecting to a domestic flight within your destination country I would always recommend to avoid flying two separate itineraries when connecting. That is because it increases the risk of you missing a flight and if you miss a flight in a situation like that you will likely have to pay for a new second flight. Also, if your luggage is lost for some reason it can become much more difficult to work through that process since it is harder to coordinate efforts to retrieve your bag.