Time is money, they say – but as far as the airlines are concerned, space is the real cash cow. Carriers are forever looking for ways to squeeze more money out of passengers, and they've started doing it by charging for everything. Making the most of every inch of packing space is a top priority for budget-conscious travelers because cramming lots of stuff into one bag means you don't have to pay for two. So-called "space bags" are one great solution, and you can absolutely take them on a plane.

What “Space Bag” Really Means

It's important to understand the different types of travel space bags, or compression bags, on the market because they don't all work the same way. Some travelers who talk about space-saving bags are talking about the kind that can be sealed using a vacuum cleaner. These bags include a special one-way valve that connects to a standard vacuum hose. When the bag is filled and the vacuum is turned on, any excess air is sucked out of the bag.

Those bags aren't commonly used now because manufacturers have started selling products that work nearly as well and are easier to use. Confusingly, you might still see space bags for sale that are called vacuum bags but don't require the use of a vacuum.

Packing Compression Bags for Flight

Compression bags are only really useful for packing clothing. Today, they're often made with a one-way valve at one end. To use this type of bag, fold or roll the clothes and place them inside the bag. Seal the bag and slowly roll it up, much as you would to get the remaining toothpaste out of an almost-empty tube. The rolling motion forces all the excess air out through the valve. These bags can be reused, and they're usually waterproof or water-resistant.

Packing cubes are another option if you're trying to fit a lot into a small bag. They're usually fabric containers that have some internal structure and zip closed. Packing cubes are great for keeping your suitcase organized, and you can use them to contain a lot of stuff, but they don't crush down to save as much space as other types of compression bags do. These cubes are ideal for holding toiletries, jewelry, shoes and other rigid items that can't be compressed.

The TSA and Vacuum Bags

As far as the TSA is concerned, you can pack 15 packing cubes in your suitcase or dump in a full laundry basket and zip the thing shut. Basically, security doesn't object to travelers using organizational cubes or space-saving bags.

If you do have any traditional vacuum-sealed bag hanging around, you might want to avoid using them when you're flying. TSA policy says that passengers are allowed to use these bags in their suitcases. However, security agents screen all bags and sometimes open those that need closer inspection. If you use traditional vacuum bags for packing and one looks suspicious on the X-ray, an agent will probably open it. Once it's opened, the bag can't be easily resealed.

Consider the Weight Issue

Using space-saving packing accessories will help you fit more stuff into your suitcase, but it won't make that stuff weigh any less. Be mindful of weight limits when using space bags for packing luggage. If you pack really efficiently, a piece of luggage that normally weighs well under the airline's weight limit could tip the scales and incur an extra charge.

The heavier the suitcase, the harder it is to lift in and out of vehicles and overhead bins. Keep that in mind too, especially if you have physical limitations.