This varies quite a bit by airport and the type of connection (domestic or international) you’re trying to make. If the airport layout requires passengers to exit one terminal and enter another between flights (often the case with international connections), that may mean going through security a second time—which may take a while. If you’re traveling on two different itineraries, you’ll need to allow for additional time to go through baggage claim (if you’re checking a bag) and security between flights.
In most cases, one hour should be enough for a domestic-to-domestic connection or a domestic-to-international, but check the airport’s website for a minimum suggested time to allow for a connection. If you’re connecting from an international flight to a domestic one, however, you could need a few hours, as we’ll explain below.