Measure linear inches for luggage by adding up the measurements of a suitcase's height, width and depth and comparing the result to an airline's requirements. Airlines typically limit the size of carry-on luggage based on measurements in linear inches.Continue Reading
Use a tape measure or ruler to measure the height, width and depth of your suitcase.
Add together the height, width and depth measurements. The total number is the linear measurement of the suitcase.
Check the carry-on requirements of the airline on which you plan to fly. Most airlines allow carry-on luggage with a maximum linear measurement of 45 inches, but some airlines set their own standards.