Place your luggage on a flat surface and keep it in an upright position for accurate measurement of its three dimensions.
Measure and list down its length from end to end using a measuring tape. It is best to take both measurements in inches and millimeters so that you have figures for both units. Although you can always measure your luggage again if needed, it is ideal to have these measurements handy at any given time, especially when the airline you use for a particular trip only provides one unit of measurement.
Measure and list down its width. Make sure that you get the measurement for a fully-packed suitcase as this may have a minimal difference with the measurement of an empty one.
Measure and list down its height. Ideally, take a measurement going past the zipper and the top corner area of the luggage.
Add the three dimensions of the baggage for each unit of measurement and check with your airline if your baggage is within their baggage requirements. Additionally, you should also weigh your fully-packed luggage on a scale to obtain its weight in pounds and kilos as this is also crucial to any airline's baggage requirements.
