The outdoor expert’s guide to washing a sleeping bag

Our LFTO outdoor sleep expert walks you through exactly how to wash and care for your trusty sleeping bag

How to wash a sleeping bag cover image

by Fliss Freeborn |
Updated on

Sleeping bags should be a cocoon of caterpillar comfort after a day of adventure, but over time, dirt, sweat, and the occasional half-eaten biscuit can turn them into less-than-fresh habitat for your overnight metamorphosis.

Knowing how to clean your sleeping bag properly is essential to maintaining its performance and prolonging its lifespan. Whether you’ve got a down-filled or synthetic bag, this guide will take you through the ins and outs of washing, drying, and caring for your sleeping bag.

Why washing your sleeping bag matters

OEX Leviathan EV 900 Down sleeping bag
©LFTO

Like many other bits of outdoor gear including tents, bikes, fleeces and boots, a clean sleeping bag not only smells better than a dirty one but also performs better. Dirt and body oils can degrade insulation over time, reducing the bag’s ability to trap heat. Regular cleaning ensures your sleeping bag stays warm, fluffy, and ready to keep you toasty on your next adventure.

However, washing a sleeping bag isn’t as straightforward as throwing it in the machine with your other laundry. The materials—whether down or synthetic—require specific care to avoid clumping, tearing, or losing their loft. Let's get into some more details.

How often should you wash your sleeping bag?

Packing a sleeping bag while wild camping
©LFTO

The golden rule is to wash your sleeping bag sparingly. Frequent washing can break down insulation and damage the delicate fabrics, especially with down-filled bags. If your sleeping bag gets some sort of muck on it, spot clean it first. Using a damp cloth, dab at stains or areas where sweat or tomato ketchup have accumulated, such as the hood or collar.

After around 30 nights of use, it's probably time you gave your bag a deep clean - either by hand or in the washing machine, and if your bag smells funky or feels dirty when you take it out of storage, it’s time for a wash too.

Pro tip: Use a sleeping bag liner on trips to minimise dirt and oils, extending the time between washes. We love a silk one for comfort and wicking abilities, but synthetic or polycotton ones are usually a little cheaper.

Washing down vs. synthetic sleeping bags

Rab Alpine 800 Down sleeping bag
©LFTO

Down Sleeping Bags

Down sleeping bags are renowned for their luxurious feel, lightweight design and exceptional warmth, but they require careful cleaning to maintain their performance. The delicate down feathers inside are prone to clumping when wet, and improper washing techniques can really mess with their insulating properties. To clean a down sleeping bag effectively, it’s essential to use the right products and handle it with care.

Thermarest Saros OF sleeping bag
©LFTO

Begin with a down-specific detergent, such as Nikwax Down Wash or Grangers Down Wash, which is specially formulated to preserve the feathers’ loft and water-resistant qualities. When washing, be gentle to avoid damaging the delicate down clusters; harsh spin cycles or wringing the bag should be avoided.

After washing, use extra rinse cycles to ensure all detergent is thoroughly removed, as any residue left behind can attract dirt and diminish the bag’s performance over time.

Synthetic Sleeping Bags

Vango Thermocore XPD in use
©LFTO

Synthetic sleeping bags are a durable and user-friendly option, making them particularly well-suited for beginners or trips to damp environments. Unlike down bags, the insulation in synthetic sleeping bags is less prone to clumping when wet, which simplifies the cleaning process and ensures consistent performance even in challenging conditions. This robustness adds to their appeal for those seeking reliable, low-maintenance gear.

When cleaning a synthetic sleeping bag, use a mild, non-bio detergent or a specialised product designed for technical gear, such as Nikwax Tech Wash. These products help maintain the bag’s performance while being gentle on its materials.

While synthetic bags are generally more resistant to wear and tear during machine washing compared to down bags, it’s still essential to follow the manufacturer’s care instructions to maximise their longevity and functionality. With proper care, synthetic sleeping bags can provide warmth and reliability for countless adventures.

Step-by-Step Guide to Washing Your Sleeping Bag

Washing machine shot sleeping bags
©LFTO

Before anyone thinks about getting wet:

  • Check the care label: Always follow the manufacturer’s instructions.

  • Inspect for damage: Look for small tears or loose stitching and repair these before washing to prevent further damage. It's really not fun having damp feathers pour out everywhere. Ask us how we know.

  • Pre-treat stains: Use a mild stain remover or diluted detergent (Fairy is fine) to tackle stubborn spots

Machine washing your sleeping bag

Machine washing is quicker and can be done if your washing machine is large enough to accommodate the sleeping bag without cramming it in. A thick synthetic bag, or a double sleeping bag, may not have room to move, so do check. Other other top tips include:

Use a front-loading machine: Top-loaders with agitators can tear the fabric or insulation. Most washing machines in the UK are front-loading, so you probably needn't worry.

Use the right detergent: Down wash for down bags, and technical wash for synthetics.

Extra rinse cycles: Run an additional rinse to ensure no soap residue remains, as this will hinder drying

Which wash cycle?

How to wash a sleeping bag_ washing machine settings
©LFTO

When machine washing your sleeping bag, the right wash cycle is very important. Always choose a delicate or hand-wash cycle to minimise agitation, and pick a very slow spin to reduce stress on the material.

Temperature should be considered too: use cold or lukewarm water to avoid damage to the fabric or insulation. Anything between 20-30c will be ok.

Hand washing your sleeping bag

sleeping bag in a bath shot 2
©LFTO

Hand washing is the gentlest method and often the safest, particularly for down bags. Here's a step by step guide.

  1. Fill a bathtub or large basin with lukewarm water and add the appropriate detergent (a down cleaner is great, or a gentle non-bio laundry detergent).

  2. Submerge the bag: Gently knead the sleeping bag to distribute the detergent evenly.

  3. Soak: Let it soak for 15-30 minutes.

  4. Rinse thoroughly: Drain the soapy water and refill the tub with clean water, repeating until no detergent remains.

  5. Carefully remove water: Press the bag gently to remove excess water—never wring it out or you'll damage the shape of the feathers. Being gentle is key, here!

How to dry your sleeping bag

OEX Leviathan EV 900 Down sleeping bag
©LFTO

Drying your sleeping bag properly is every bit as important as washing it. If done incorrectly, you risk ending up with a lumpy, damp, or even damaged bag. A large-capacity tumble dryer is the ideal tool for the job. Set it to the lowest heat setting to protect the delicate insulation, whether down or synthetic.

To restore the bag’s loft and ensure the filling doesn’t clump, toss in a few clean tennis balls or dryer balls. Drying a sleeping bag isn’t a quick task—it can take several hours—so be prepared to check on it periodically. Stop the dryer now and then to fluff and redistribute the filling, ensuring an even and thorough dry.

If a tumble dryer isn’t available, air drying is a slower but effective alternative. Lay the sleeping bag flat on a clean, well-ventilated surface. If you can lie it flat on a whirlygig style washing line, or drape it over the arms of several drying racks, then great - but don't just fling it over the top of a single line as the filling will distribute unevenly. Throughout the drying process, fluff the bag gently to prevent clumping and to encourage airflow.

Patience is key, especially with down bags, as drying this way can take 24–48 hours. Resist the urge to rush; a little care here can mean the difference between a bag that performs well and one that doesn’t.

The long term

Rab Alpine 800 Down sleeping bag
©LFTO

To extend the life of your sleeping bag and minimise the need for frequent washes, take steps to keep it clean and store it correctly. A sleeping bag liner is a simple and effective way to create a barrier between your body and the bag, reducing the buildup of dirt and sweat. For smaller stains or spots, act quickly with spot cleaning to prevent grime from settling into the fabric.

When it comes to storage, always keep your sleeping bag in a large, breathable sack instead of compressing it into a tight stuff sack for long periods. Proper storage preserves the loft and ensures the bag remains ready for your next adventure. Finally, be mindful of exposure to harsh conditions. Prolonged UV light or damp environments can degrade the materials over time, so store your bag in a cool, dry place. With thoughtful care, your sleeping bag can stay cozy and reliable for years to come.

Final thoughts

Washing your sleeping bag doesn’t have to be a pain in the baffles. With a bit of care and attention, you can keep your snuggly haven fresh, warm, and ready for many more adventures. Whether it’s a luxurious down bag or a rugged synthetic one, following the right cleaning and drying techniques will help your bag perform at its best, trip after trip.

About the author

Fliss Freeborn LFTO writer

Fliss Freeborn is LFTO's hardcore camping enthusiast. She has washed many a sleeping bag in her time, and absolutely loves to snuggle down in a pile of duck feathers on a cold, winter's night.

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