How Many Vacuum Bags Do You Need, and What Size? A Guide by Bag and Trip Length (2026)

Most travellers need two vacuum bags for a backpack, three or four for a carry-on, and six to eight for a large checked case. That is based on travel bags of about 12 by 19 inches, the size Aerless and Ekster both sell, and Aerless's own chart shown above. Trip length matters less than you would think, because after about a week you do laundry rather than pack more. This guide covers how many bags to buy, what size, and how to fit them in your luggage. The numbers come from the brands' own size guides and our reading of published tests, not from our own packing trials. For the kit these figures come from, see our Aerless vacuum bags review.

How many vacuum bags fit in each type of luggage?

The upper figures assume you fill each case mainly with bags. Leave room for shoes, wash bags, chargers and anything hard, which do not compress and fit best in the gaps around the flat packs.

How many vacuum bags do you need for your trip?

Past about ten days, the number of bags stops growing, because you wash clothes rather than carry more of them. What changes on a long trip is how hard the bags work: they get opened and closed far more often, so sturdy nylon with a slider zip is worth more than a cheap set.

How to work out how many bags you need

1. Lay out everything you plan to take. Separate bulky, airy items (jumpers, fleeces, puffer jackets, hoodies) from dense ones (jeans, shirts, shoes).
2. Count only the bulky pile for vacuum bags. Dense items compress very little, so they are better loose or in packing cubes.
3. Allow about 15 light items, or two or three bulky ones, per bag. That is Aerless's figure for a 12 by 19 inch bag: about 15 T-shirts and light layers, or two or three bulky jumpers.
4. Add one bag for the trip home. A spare bag holds worn clothes, keeps smells in and makes room for anything you bring back.
5. Check the result against the luggage table above. If you need more bags than your luggage holds, the problem is the packing list, not the bags.
6. Weigh the packed bag. Vacuum bags make clothes smaller, not lighter. Our article on whether vacuum bags make luggage lighter covers carry-on weight limits by airline.

What size vacuum bags should you buy?

Match the bag to the inside of your luggage. A bag that lies flat across the base of the case packs better than one that has to bend. For most carry-ons, bags of about 12 by 19 inches (30 by 48 cm) fit side by side or stacked.

Several medium bags beat one large one. Two or three medium bags fit around shoes and wash bags, let you sort clothes by type, and let you open one without unpacking everything. A single large bag leaves gaps and becomes a hard slab that is awkward to pack around.

Home storage bags are usually too big. Vacuum bags made for duvets and seasonal storage are often 30 inches or more across, which is too big for luggage. They also need a vacuum cleaner to compress again.

The litre figure is a rough guide. Brands quote the capacity of the bag before it is compressed, and the figures vary: Ekster lists the same 12 by 19 by 4 inch bag at 19.5 litres on its site and 27 litres at retailers. Go by the flat dimensions instead.

Example: packing a 40-litre backpack

A 40-litre travel backpack, the most common one-bag size, has room for about two 12 by 19 inch vacuum bags. A workable layout for a week:

1. Bag one, at the back against your spine: a fleece, a jumper and two long-sleeve tops.
2. Bag two, on top of it: five T-shirts and a lightweight jacket.
3. Loose around them: underwear and socks in a small cube, a pair of trousers, a wash bag and chargers.
4. In the front pocket: the pump, if your kit has one, plus anything you need at security.

Packing the flat bags against the back panel keeps the weight close to your body and leaves the softer items to fill the curves of the pack. More than two bags in a 40-litre pack usually makes it rigid and harder to close. Our guide to using Aerless vacuum bags covers how to stack bags in luggage.

Which kit to buy for that number of bags

Kits are sold by bag count, and the price per bag falls as the kit grows, because the pump is the expensive part. On 6 October 2026, Aerless sold one bag with a pump for $69, two for $89, four for $129 and six for $159; Ekster charged $79, $99 and $149 for one, two and four. For a carry-on, the four-bag kit is the best buy from either brand. For two people sharing a case, one six-bag kit and one pump is cheaper than two smaller kits. Our roundup of the best vacuum compression bags for travel compares the kits.

Our verdict

Buy two vacuum bags for a backpack, four for a carry-on and six for a checked case, and add bags only if your trips are cold enough to fill them with bulky layers. Trip length matters less than the type of clothes: a month of summer travel needs no more bags than a week, while a single week of skiing can fill eight. Start with the four-bag kit if you are unsure. It covers most trips, and you can buy spare bags later.