Measure the length, the width and the height of your suitcase or piece of luggage.
Add up the dimensions of your suitcase (length + width + height) to ensure that the total is no more than 62 inches. Items over 62 inches may be checked, as long as they are under 80 inches, for a $50 fee. Because ticket-counter representatives will not measure your bag at check-in, you should be fine if you are a couple of inches over. Carry-on luggage must be no larger than 10 by 16 by 24 inches, or 50 inches total.
Weigh your luggage on a regular household scale. Bags under 50 lb. and within size restrictions are free of charge. Bags between 51 and 100 lb. will incur a $50 charge. Bags over this weight must be shipped. For carry-ons, lift your bag above your head in order to ensure you'll be able to place it in the overhead bin once on the plane. If the bag is extremely heavy, it may not be a good candidate for carry-on.