Most airlines measure check-in luggage in linear dimensions, which means the sum of the length, width and height. The most common linear limit for check-in luggage is 62 inches, though it's prudent to confirm.

Yes, airlines are increasingly strict about measuring checked luggage because their business model relies heavily on baggage fees and fuel weight calculations. While a bag might pass if it's "close enough" to the weight limit (usually 50 lbs or 23 kg), they are much more focused on "Linear Inches" (Length + Width + Height). The standard limit for most carriers is 62 linear inches. If your bag looks oversized, an agent at the check-in counter will absolutely use a tape measure or a pre-sized bin. This is because oversized bags are difficult to handle for automated conveyor systems and can take up disproportionate space in the aircraft's hold. With the rise of "self-service" bag drops, many airports have installed scanners that automatically measure the dimensions of your bag as it moves onto the belt; if it exceeds the limit, the system will halt and prompt you for an "Oversized" fee payment. To avoid a $200 surprise at the airport, it is essential to measure your bag from the wheels to the top handle before you leave home, as "visible bulk" is often what triggers an agent's scrutiny.