Many items in your home are necessities at certain times of the year but take up too much space during the off-season. When you need guest pillows or parkas, you really need them. But once their hour has passed, you need that valuable space for the next season’s essentials.

Space saver bags, however, could help you reclaim some shelf space and keep your items accessible when you need them. These are plastic storage bags that let you compress the air from bulky items, greatly reducing the amount of storage space they occupy. Most space saver bags compress using a vacuum; others use alternate methods. They’re most often used for storage, but some travelers use them to compress items to better fit into a suitcase.

Which space saver bags would work best for you? It depends on what you’re storing and for how long. Keep reading to learn more. When you’re ready to buy, check out our top picks.

• Short-term storage: Bags designed for short-term storage generally work best with clothing items. Saving suitcase space on a trip to Europe or moving a child to a college dorm requires items to be bagged for a few days or weeks. While some bags will be thick, most will be smaller and thinner, designed with packability in mind.

• Long-term storage: If you’re planning on storing items for a few months or longer, you should look at bags meant for long-term storage. Last season’s clothing, Christmas stockings, and guest bedding are generally ideal candidates for long-term storage. Bags intended for long-term use will usually be larger and thicker, with more precautions taken to prevent leaks and tears.

• Vacuum cleaners equipped with a suction hose are used to close the majority of space saver bags. They are the quickest and most efficient means of preparing bags for storage. They are, however, the hardest on the materials in the bag. They can be used with items like stuffed animals, clothing, towels, and some bedding. Vacuum bags are great for traveling because they can greatly reduce the amount of space clothing items take in your suitcase. They’re only helpful, however, if there’s also a vacuum at your destination. These bags work for both long-term and short-term storage.

• Hand pumps suck the air out of the bag, but they are not as efficient as vacuum-bag systems. However, they are gentler on your clothing. And since the pump is small, it’s easily packed for use at your destination. Hand-pump bags are not as practical for storing larger items, like bedding, but they are good for packing items like sweaters, coats, and other bulky goods. They are better for short-term storage, but, in some cases, can be used longer.

• Compression bags are used specifically for packing clothing. You roll these bags up just like an almost-empty tube of toothpaste — pushing the air out of the one-way valve. They’re not as efficient as vacuum or pump bags, but they’re even more gentle on your fabric items and are a decent choice if you’re traveling and concerned about losing your pump. They are intended primarily for short-term storage or travel.

Space saver bags come in a variety of sizes. Some are large enough to hold an entire duvet cover; others are designed to fit in a carry-on suitcase. Think carefully about the items you are going to store. When in doubt, go bigger — unless you are specifically trying to fit things into a suitcase. Overstuffing a space saver bag is one of the easiest ways to break it.

All space saver bags come with a seal — a thick strip across the top where the opposite sides lock together to keep air out. Most manufacturers affix a plastic slider that glides across the lock to ensure it’s completely closed. Some bags feature a single seal across the top; others offer two layers of protection in case one of the seals fails. Double-sealed bags are generally higher in quality than bags with a single seal.

No matter how you suck the air out of a space saver bag, it must come out of the bag’s valve. Valves are intended to be one-way — only letting air out and keeping it from re-entering the bag. Some bags have only a single seal around the valves; others have two or even three.

All valves will have some kind of protective cap that provides an extra layer of security against valve failure. Snap-on caps provide minimal protection; caps with a screw-on top create the tightest barrier against valve failure.

Many bags intended for long-term storage feature protective linings to keep their contents safe from mold and mildew as well as bacteria and microbes. Protection like this is especially important for items that will be tucked out of sight for long periods of time.

Inexpensive: The least-expensive storage bags will cost around $2.50 per bag. Some will accommodate vacuum hoses to remove air, others may simply roll, and others will use hand pumps. They will usually be smaller (making them perfect for travel) and be made from thinner materials. These bags may feature single or double seals.

Mid-range: Middle-of-the-road storage bags often cost $3 to $3.50 per bag. Bags in this price range typically seal with a vacuum hose or hand pump. They will mostly hold clothing and linens, although some may accommodate bedding. All should feature double seals; some may have special treatments to protect your items.

Expensive: Packs of high-quality storage bags cost around $5 per bag. They come in a variety of sizes, ranging from small travel sizes up to sizes that can fit a comforter, and close with a vacuum hose or possibly a pump. Bags costing this much should be made of thick, puncture-resistant material and feature reliable double seals and reinforced valve seals. They should be treated with anti-mold or mildew linings to protect your belongings and possibly include a pump or other bonus items.

• If you’re using space saver bags to pack for a trip, make sure there’s a vacuum available at your destination.

• Overfilling a bag is tempting, but it could lead to poor sealing or even damage the bag. If you’re unsure how many you’ll need, buy extra.

• Many manufacturers recommend airing out your space saver bags every six months.

• Items made from leather or fur should not go in space saver bags.

If you can’t settle on a style, this combo pack of 20 Hibag Space Saver Bags gives you some of everything at a great price. In addition to 20 vacuum bags, you get two roll-up bags and a hand pump. Colored zip lines, similar to popular sandwich bags, let you know when you’ve achieved a quality seal. Some find these bags to be an appropriate thickness for storage but question their durability for travel.

These FoolHome Hanging Vacuum Storage Bags offer intriguing possibilities for customers with limited shelf space. Not only do they have a double-zip, moisture-proof design to protect your items, but they also hang on a standard closet rod to keep them off the ground and away from leaks. Some find them a bit thin, but they may meet a need other brands do not.

Q. Why do some manufacturers warn against putting anything made with down in space saver bags?
A. Fluffy items made with down or other feathers should not be vacuum-sealed — especially for long periods of time. These items keep you warm by trapping air inside the pockets, so removing all the air can compromise their ability to keep warm air inside. Once compressed, especially for long periods, it’s hard to get them to regain their loft, which compromises their ability to insulate. If you really need to store them efficiently, either try reducing the bag down to about 50% or consider using a bag with a hand pump.

Q. Can I put garments made from natural fibers in a storage bag?
A. Many manufacturers recommend against putting animal-based materials like wool, fur, and leather in space saver bags. Wool and fur need to breathe to maintain their shapes, and vacuum bags are designed to remove all the air from the fiber and environment. Items made from these materials are better off hung up or loosely boxed rather than tightly packed.

Leather is vulnerable to irreparable damage in space saver bags. Tight bags often wrinkle or stretch leather in awkward positions, and the lay of the leather often can’t be repaired afterward. Additionally, a major gripe with virtually all space saver bags is their unexpected failure — which can expose the contents to mildew and mold. While fabric items can often be salvaged, mold and mildew usually rot leather beyond repair.

Q. Can you repair a damaged space saver bag?
A. You can, if the hole is small enough. But finding it might not be easy. Before you try more drastic measures, fill your bag with air, examine it, and listen for hissing. If you can’t find the leak that way, consider filling it with air and submerging it in a tub of water. Look for bubbles escaping from the bag to the surface of the tub — the air leak is the source of the bubbles. You may be able to repair the hole with duct tape, if it’s small enough. If you use the water method to locate your tear, be sure to dry your bag thoroughly before repairing and using it because hidden water can lead to mold and mildew, damaging the contents. Only take these steps if you’ve already used your bags; fixes like these may not work for long. If you have a leak in a new, unused bag, talk to the manufacturer about a replacement.