Guide to Change Flights

1Book online if possible. When they list the flights, they usually include how long each layover is.

2Many airline shut their doors 10 minutes prior to departure. Keep this in mind when booking.

3If you are connecting to a different airline, you may need to switch terminals. In that case, you will need to allow plenty of time to go through security.
Some airport websites (such as London Heathrow) have a calculator where it can give you an estimated time when connecting from one terminal to another (for instance Terminal 1 to Terminal 5.)
If you are staying on the same airline, usually the gates are all in one area (USUALLY!!)
Some airports, like Washington Dulles, have United Airlines, for instance, in C and D... and if you're connecting flight happens to be in the other terminal, you have to take the SLOW people mover. Allow PLENTY of time (15-20 minutes) for you to be able to connect via people mover if needed.

4If you have children, make sure there is enough time for them to stretch their legs... but not so much time they are bored out of their minds.