On my first trip overseas, I packed a suitcase the size of another human. When I collapsed halfway up a never-ending staircase climbing out of a metro station with no elevator, I developed the Only Rule of Packing: pack what you can carry, picture dragging it up five flights of stairs, then pack less.
Following this rule, I can usually manage with a carry-on bag only for trips under two weeks. I still might check the bag, but that depends on a variety of factors.
The case for carry-on:
You don’t have to show up early to check your bag. So if you get CLEAR, as I recommended here, you can roll into the airport 45 minutes before your (domestic) flight and be golden.
You don’t have to wait for your bag at baggage claim, which can sometimes take a half hour plus.
The airline can’t lose your luggage.
You have more flexibility if things go wrong with your travel plans if you only have carry-on luggage. For example, Washington has three airports (DCA, Dulles, and BWI). If your flight from wherever to DCA is canceled, you might be able to fly home to Dulles or BWI instead, but it’s a lot easier to get the airline to make that switch if all of your baggage is with you.
Airlines, in their quest to make flying as miserable as possible, may have steep fees to check bags and even steeper fees if your bags are overweight.
Circumstances that may warrant checking a bag:
When flying to smaller cities on regional jets or prop planes, the overhead may not accommodate roller bags. In this case, the airline usually gate checks the bag, meaning you stand in a line by the plane door after the flight waiting for your bag. That’s a good way to miss your connecting flight if you’re on a tight timetable. So pay attention to your aircraft type/layover time and either carry-on a soft sided bag like a backpack or duffle bag or check your bag.
Airlines in other countries may be stricter with the size and weight of your carry-on baggage so checking the bag regardless of size may be advantageous. Normally, you get one free checked bag on an international flight, but this will vary by airline.
Even if you can check a giant bag for free, remember the five floor exercise before overpacking.
If you are not flying direct, consider how much time you have for a connection and whether you have to go through security again. As I learned while transferring in London on my to Norway, I should have checked my bag because the extra screening time caused me to miss my connecting flight.
If you are planning to bring home liquids (Kentucky Bourbon, French champagne, California wine, etc.) you can’t put those in your carry-on so you’ll have to check. Because I pack lightly, I rarely fill a larger 25/26 inch suitcase. BUT, that means there is plenty of room for wine.
If you do check your main bag, never assume it will arrive. Keep certain essentials like medication, glasses/contact solution, and spare undergarments in your carry-on.
Also keep in mind that trains are usually much more generous on how much and how free your baggage is, but remember the five floor exercise before overpacking.
If you want to avoid fees, be aware:
Some budget airlines now charge for carry-on bags (I personally do not travel on these airlines. Some consumers may find the cost savings on the ticket price worth it. I don’t.).
The big U.S. airlines have also started to offer tickets that do not include a carry-on. Make sure to pay attention to the type of ticket you bought and check your airline’s baggage policy before going to the airport.
If you are traveling internationally and flying to more than one country as part of your itinerary, you may be considered on a “domestic” flight and have different baggage rules apply. For example, you fly from the USA to France and then from France to Germany. Likely, the flight from the USA to France will come with a free checked bag, but the flight from France to Germany may be considered “domestic” and come with bag charges. Check your airline’s policy to make sure your bag fits size-wise and weight-wise.
If you want to avoid checked baggage fees and plan to fly the same airline most of the time, you can also look into airline credit cards or work toward status on an airline to get free checked bags.
Checked and carry-on bags are still free on Southwest (they did not pay me to mention this).