The United Airlines Baggage Policy has a simple policy that is intended to simplify your travel arrangements. Generally, travelers are only permitted to check in one carry-on bag and one personal item such as small suitcase or laptop bag for free. Destination fare class and MileagePlus status all affect checked baggage costs with the majority of economy travelers having to pay for their first checked bag. If you need to check more bags or if your luggage is large or overweight there will be additional costs.