Your Ultimate Guide to Carry-On Luggage Guidelines

Even if you've mastered your packing techniques, you've likely encountered a carry-on bag that just won’t fit into an unexpectedly cramped overhead bin while a flight attendant watches disapprovingly. Even worse, you may have had to gate-check your bag when it didn't fit snugly into the dreaded measurement box. Did the airline’s website downplay how strictly gate agents enforce size restrictions, or did you simply forget to verify?

Carry-on luggage rules differ by airline, aircraft type, and even ticket class—meaning the suitcase you took on one flight could be gate-checked on another depending on size or weight limits. Before your next journey—whether it's within the United States or on multiple international flights—refer to this guide to ensure your bag fits in the overhead compartment.

What should the dimensions of your carry-on luggage be?

For domestic flights within the United States, a carry-on bag measuring less than 22 x 14 x 9 inches (45 linear inches), including handles and wheels, will comply with the size requirements of all major airlines like United Airlines and Alaska Airlines. While some airlines—such as Southwest and Spirit Airlines—permit bags up to 50 linear inches, it’s wise to choose a bag around 45 linear inches or smaller if you’re in the market for a new carry-on and expect to fly with various airlines.

Size restrictions vary significantly on non-U.S. airlines, but unless you're flying on a small island-hopper in the Azores, a bag of 45 linear inches or smaller will meet the requirements of nearly all airlines.

Carry-On Luggage Weight Restrictions

Most major U.S. airlines, excluding Frontier and Hawaiian Airlines, typically do not impose a weight limit on carry-on bags. However, travelers must be capable of lifting their own bags into the overhead bins, as flight attendants are generally not able to assist. Delta's spokesperson Ben Zhang emphasizes his airline's clear policy, stating that “flight attendants cannot proactively assist customers with placing carry-on baggage into overhead compartments, except in specific circumstances.” Assistance is available for passengers with disabilities under the Airline Passengers with Disabilities Bill of Rights, which mandates that airlines “must provide assistance upon request, such as . . . stowing and retrieving carry-on items, including assistive devices.”

In contrast, many airlines outside the USA enforce weight limits for carry-on luggage, varying from 11 pounds (Air China) to 51 pounds (British Airways). Numerous budget airlines, both domestically and internationally, have stringent regulations and fees regarding the quantity and size of carry-on bags and strictly enforce these policies, so it's crucial to verify your specific airline's guidelines when traveling overseas.

Carry-On Size Regulations for Major Domestic Airlines (USA)

The dimensions and weight limits for carry-on bags in the following tables apply primarily to standard economy tickets (though certain airlines, like Spirit and EasyJet, charge for carry-on luggage beyond a personal item). Some airlines may permit extra carry-ons, larger bags, or bags exceeding standard weight if you have booked a premium economy, business, or first-class ticket.

Carry-On Dimensions for Major International Airlines Leaving the United States

What is the Carry-On Allowance?

Most leading domestic and international airlines permit economy class travelers to bring one carry-on bag and one personal item. (Business, first, or premium class passengers generally have a higher allowance.) Basic economy tickets usually permit only a personal item, with no access to the overhead bins.

What qualifies as a personal item?

A personal item must fit beneath the seat in front of you and typically includes things like purses, small handbags, backpacks, briefcases, and laptop cases. Some airlines also allow diaper bags, cameras, and duty-free goods—or items purchased within the airport—along with a carry-on and personal item. Additionally, many airlines will gate-check strollers.

How to Properly Measure Your Carry-On Luggage

To determine the dimensions of your carry-on bag, measure its length, height, and depth (or width) . Sum these three measurements to get the total linear inches. For instance, a bag measuring 20 inches in length, 12 inches in width, and 6 inches in depth would total 20+12+6 = 38 linear inches.

If a measuring tape isn’t available, you can usually find the dimensions of your bag on the seller’s product page online under specifications. Many bags also display dimensions on the hang tag, so keep it instead of discarding it after purchase—tuck it into a pocket for easy access when needed. Most airlines offer boxes at check-in where you can test your carry-on size to ensure it fits in the overhead compartment.

What Qualifies as a Carry-On?

Typically, a small rolling suitcase, duffel bag, or larger backpack is considered a carry-on. Garment bags are also classified as carry-ons, provided they meet the airline’s size requirements. For example, American Airlines permits passengers to bring a soft-sided garment bag up to 51 inches instead of a standard piece of luggage.

By law, airlines must allow passengers to bring a small musical instrument as a substitute for a carry-on bag, as long as it fits under the seat or in the overhead compartment. Travelers might consider a preboarding option to secure space for their instrument, though this is not guaranteed.

Travelers can purchase an extra seat for larger instruments (like a cello) if they comply with the airline’s size and weight restrictions. Military bags and sports gear are also accepted as carry-on luggage, although larger items—such as surfboards, golf clubs, and hockey equipment—might incur standard checked baggage fees, depending on the airline’s carry-on policies.

What Can You Bring in Your Carry-On and Personal Item?

Carry-on bags must pass through airport security, so they cannot contain hazardous materials or large quantities of liquids. According to the TSA’s 3-1-1 liquids rule, liquids are limited to 3.4 ounces (100 ml) per item, must fit in a quart-sized plastic bag, and each passenger is allowed one quart-sized bag.

Generally, food is permitted in your carry-on, although some items may fall under the TSA’s liquids regulations—similar to your toothpaste. Surprisingly, peanut butter is classified as a liquid because, as the TSA stated, it lacks a definite shape and conforms to its container. This is just one of the many unexpected items the TSA restricts from onboard carry-on luggage.

Carry-on luggage is prohibited from containing sharp objects, explosives, or flammable substances, though some of these items may be allowed in checked baggage. If you're unsure about a specific item, the TSA’s What Can I Bring? website is a useful reference.

If you're struggling to fit everything into your carry-on, consider using packing cubes, which not only maximize space but also help keep your items organized. Alternatively, you can avoid luggage hassles altogether by shipping your bags and traveling light with just a stylish fanny pack.

This article was originally published in 2019 and updated most recently on January 3, 2024, to reflect the latest information.