There are 3 levels to an FAA medical. Class 1, 2, & 3; 1st Class is for airline captains, 2nd is for commercial pilots flying for hire, 3rd class is for Private & Recreational Pilots.
We recommend getting your 1st class to begin with. This ensures that the process will be much easier when you do become captain at an airline.
*NOTE* INFORMATION ONLY APPLIES TO PERSONS UNDER 40: You may see that 1st class only lasts for 12 months. This is true, however, after the first 12 months, the medical will then downgrade to a 3rd class for 48 months (5 total years of medical). If you opt for getting a 3rd Class, this will be valid for 60 months (5 years).
*NOTE* INFORMATION ONLY APPLIES TO PERSONS OVER 40If you are over 40 it is still beneficial to get the 1st class to start off if you plan on going to the airlines. The only difference is the 1st class is valid for 6 months but you can exercise 3rd class for 24 months (2 years).