Rules for Carryon Luggage to Live By

You know the moment when you’re trying to fit your carry on bag in the overhead bin, only for the horrible realization that it won’t fit? Or when you’re preparing to board a plane only for the attendants to tell you that your bag doesn’t qualify as a carry on? 

We’ve been there. Fees for checked bags are nobody’s idea of a good time, especially not budget travelers. 

The first step to mastering carry-on-only packing is to know the rules.

Carry on luggage allowances differ by airline. Check your airline’s rules before flying. Just Google “[airline] carry on luggage” or “[airline] hand luggage.”

Always use the measurements from your airline’s website. Those measurements will be the most accurate. While there are broad rules for carry on bags, the rules often vary by airline (especially budget airlines like Ryanair). 

If you’re flying connections with multiple airlines, check the restrictions for each airline. Your baggage must meet the requirements for all of your flights, so use the strictest one as your guideline. 

Be wary of third-party sites that aggregate information for multiple airlines as their measurements may be inaccurate or outdated, turning carry on bags into checked bags in the blink of an eye.

Carry On Luggage Size

The most commonly allowed size for carry on luggage is 45 linear inches (length + width + height).

Some airlines allow larger bags, but 45 inches is a reliable baseline to use. Keep in mind that European airlines have smaller bag size restrictions than the United States, usually 35 linear inches

Airlines that give measurements by dimension typically allow bags up to 22 x 14 x 9 inches. Some airlines allow bags that are larger in one or more dimensions, but this configuration will meet the guidelines for most major airlines. We used these measurements to maximize packing space in the Outbreaker Backpack while still keeping it carry-on-eligible on most airlines.

Budget airlines like Ryanair are the most common exceptions to these norms. Cheaper airlines are often more strict with luggage size rules and more likely to force you to check a carry on bag. 

Happily, the Outbreaker 35, the smaller, lighter of the two travel backpacks in the Outbreaker Collection, is perfectly suited to the more restricted size guidelines on budget airlines. All you have to do is pack what you need. 

Check your favorite airlines’ rules before buying new luggage. If you’re traveling on multiple airlines, use the strictest guideline. If you’re flying with a budget airline, be prepared for stricter guidelines than usual. 

In addition to your carry on luggage, most airlines also allow one personal item, like a purse, daypack, or laptop bag. Your personal item must fit under the seat in front of you. Very few airlines publish size rules for personal items. United’s new baggage policy allows items up to 17 x 10 x 9 inches. If your airline doesn’t have specific size limits, use United’s rules as a guide to determine if your personal item will fit under the seat. If in doubt, make a conservative estimate

Carry On Luggage Weight

Carry on luggage weight rules vary even more than size rules.

Some airlines allow carry on bags weighing up to 50 pounds. Even if you’re allowed to carry 50 pounds, you probably shouldn’t do it. Lugging that much weight around defeats the purpose of packing light, and even the most ergonomic carry on bag will be heavy to haul at 50 pounds. 

Instead, aim for the low-end of allowed weight: 18-25 pounds. This means only packing items you can’t live without, cutting out as many liquids and gels from your toiletries as possible, and maxing a smart use of your available space. 

Some budget, European, and Asian airlines only allow carry on bags up to 15 pounds. If you’re not sure about your airline, make a conservative estimate. Make sure to check with your airline before flying. A $20 electronic luggage scale will pay for itself by helping you avoid fees for overweight luggage.

Carry On Toiletries Size

The rules for carry-on-sized toiletries in the United States are set by the Transportation Security Administration (TSA). Toiletry size rules are consistent around the world.

The rule for toiletries is 3-1-1:

  • 3.4 ounce (100ml) bottles or less (by volume)
  • 1 quart-sized, clear, plastic, zip-top bag
  • 1 bag per passenger

Your liquids and gels must be in 3.4 ounce (or less) bottles. Those bottles must fit into a one quart plastic bag. Each passenger may only carry one such bag.

For more details on these rules, refer to the TSA’s website.

Frequent travelers should consider applying for TSA PreCheck. Once approved, you’ll have access to an expedited screening process including a separate security line. In the PreCheck security line, you can leave your laptop and liquids in your bag and don’t have to take off your jacket or shoes.

PreCheck is the closest you can get to being treated like a human being at the airport. The PreCheck program costs $85 for 5 years. If you travel abroad, join Global Entry. Global Entry offers all of the benefits of PreCheck plus expedited re-entry into the United States for $100 for 5 years.

As for toiletries themselves, don’t be that person rooting around for their toiletry bag in the security line. Keep your toiletries to the minimum and make sure they’re easy to access. 

Before flying, always check your airline’s carry on luggage size and weight guidelines.

A good rule of thumb is that your carry on luggage can be up to 45 linear inches (length + width + height). The most common configuration is 22 x 14 x 9 inches, the dimensions of the Outbreaker Backpack.

Don’t pack 50 pounds even if it’s allowed. Instead, keep your luggage to under 25 pounds. All toiletries must be in 3.4 oz (100 ml) or smaller bottles. Those bottles must be in a single quart-sized, clear, plastic, zip-top bag.


Get a Free Carry on Packing List

Join our email list for more packing tips and gear guides.

When you sign up, we’ll send you a free carry on packing list to get started.