Luggage Size Calculator

Linear inches: the number airlines use

Airlines do not measure your bag the way you do. They add the three dimensions together and compare the total, called linear inches, to a limit. That is why a long, thin duffel can be rejected while a squarer bag of the same volume sails through.

The two limits that matter most for US domestic travel:

• Carry-on: usually 22 x 14 x 9 inches, or 45 linear inches, and about 22 pounds, though some airlines allow 25 to 35 pounds.
• Checked: usually 62 linear inches and 50 pounds before overweight fees start.

The calculator above adds your bag's dimensions, compares the total to both limits, and flags which class your bag falls into: personal item, carry-on, checked or oversize.

Worked example: is a 24-inch roller bag a carry-on?

A common 24-inch roller bag is about 24 x 16 x 10 inches. Let us run it through:

• Linear inches: 24 + 16 + 10 = 50 linear inches
• Carry-on limit: 45 linear inches (22 + 14 + 9)
• Result: 50 is 5 inches over the carry-on limit

That bag is a checked bag, not a carry-on, even though the store may have labelled it carry-on friendly. A true carry-on is the 20-inch class, about 22 x 14 x 9 = 45 linear inches. The 24-inch size is the most common checked bag in the US and fits within the 62-linear-inch checked limit with room to spare.

Now the weight. A typical empty 24-inch roller weighs 8 to 10 pounds. Packed for a week it easily hits 45 pounds, which is under the 50-pound limit, but pack for two weeks and you can cross 50 and pay $100 or more each way. The calculator shows your headroom against the limit so you can weigh before you leave.

Personal item, carry-on and checked: the limits

The standard US domestic figures, from smallest to largest:

These are the standard US domestic figures. International and budget carriers vary: a European low-cost carrier may cap carry-ons at 55 x 40 x 20 centimeters, and some US airlines treat 22 x 14 x 9 as a hard rule measured in a sizer at the gate. The TSA screening rules are separate from size limits and apply to what is inside the bag, not its dimensions.

Weight limits and what overweight costs

Size gets you past the sizer; weight gets you past the scale. US airlines commonly charge $30 to $40 for the first checked bag, $40 to $50 for the second, and $100 to $200 for a bag over 50 pounds. A bag over 70 pounds is often refused outright regardless of what you offer to pay.

The math is unforgiving. A 55-pound bag on a route with a $100 overweight fee costs more in fees than shipping a 10-pound box of clothes ahead. If you travel with a heavy bag regularly, a 26- or 28-inch bag lets you spread the same weight across more space and stay under 50 pounds more easily, but check the 62-linear-inch limit, because a 28-inch bag at 28 x 20 x 12 = 60 linear inches is right at the edge.

Two practical habits: weigh your packed bag on a bathroom scale before you leave, and keep one change of clothes in your carry-on so a delayed checked bag does not ruin a trip.

How to measure a bag and avoid gate fees

Five steps keep you out of the fee column:

• Measure the outside, including wheels and handles. That is what the gate agent measures. A bag advertised as 22 inches may be 24 with the wheels and handle included.
• Add the three numbers. Length plus width plus height, in inches. That is your linear inches.
• Compare to your airline's own published limit, not a generic chart, because they differ.
• Weigh it packed. Use a bathroom scale: you holding the bag, minus your own weight.
• Check the sizer at the gate. If it fits the airline's sizer, you are fine; if the agent asks you to try and it does not fit, you pay.

Gate-checking a bag that does not fit is usually cheaper than paying at the counter, but it means parting with the bag at the gate and hoping it makes the connection. The FAA traveler information pages cover the safety side of what can and cannot fly, and your airline's own baggage page is the only authority on size and weight for your specific ticket.

What the major airlines allow

Size and weight limits are set by each airline, not by a single standard, and the differences add up. Here is how the common US carriers compare on the numbers most travellers run into:

The practical rule is to check your specific airline's baggage page before you fly, because a limit that worked on one carrier may not on the next. Two patterns are worth remembering. First, mainline carriers are more generous on carry-on weight than budget carriers, which sometimes weigh bags at the gate. Second, international and long-haul fares often allow more checked weight than domestic ones, so a bag that is overweight on a domestic leg may be fine once you are on the international portion.

One more comparison worth making is the carry-on sizer. Even when two airlines publish the same 22 x 14 x 9 limit, the physical sizer at the gate can be a fraction smaller, because it has to accommodate a handle. A bag that measures exactly 45 linear inches at home may need a firm push to fit, so leave an inch of margin if you can.

If you are close to a limit, weigh and measure at home. A soft tape measure and a bathroom scale cost nothing and settle the question long before you are standing at a counter with a queue behind you.