Choose down if you want the most warmth for the least weight and packed size, and you can keep your bag dry. Choose synthetic if you camp in wet, humid conditions, want a lower price, or need a bag that’s easy to wash and forgiving to care for. Down is the backpacker’s favorite; synthetic is the practical pick for car camping, damp climates, and kids.
Quick answer: who should pick which
- Down: backpackers, cold weather campers, and anyone who wants a bag that lasts many seasons with good care.
- Synthetic: campers in rainy or humid areas, paddlers, budget buyers, families, and anyone who sleeps in damp shelters or under the stars.
Down vs synthetic at a glance
| Attribute | Down | Synthetic |
|---|---|---|
| Warmth for its weight | Excellent | Good |
| Weight class | Lighter for the same rating | Heavier for the same rating |
| Packed size | Very compressible | Bulkier |
| Performance when wet | Loses loft and warmth; treated down resists moisture better | Keeps some warmth when damp and dries faster |
| Durability and lifespan | Long lasting with proper care | Loses loft sooner with repeated compression |
| Care | Needs careful washing and thorough drying | Easier to wash and dry |
| Cost level | Moderate to high | Low to moderate |
| Best use | Backpacking, dry cold, high elevation | Wet climates, car camping, kids, budget trips |
Down sleeping bags
Down is the soft underfeathers of ducks and geese. It traps warm air in tiny pockets and lofts up high. Quality is measured by fill power: a higher number means more loft per ounce, so the bag can be lighter for the same warmth.
Pros
- Best warmth for its weight of any common insulation.
- Compresses small, saving pack space.
- Lasts many years if you store and clean it properly.
- Comfortable across a wide temperature range.
Cons
- Clumps and loses much of its warmth when wet.
- Costs more, especially at higher fill power.
- Takes longer to dry after washing.
- Not an option for people with down allergies or those avoiding animal products. If sourcing matters to you, look for a responsible down certification.
Who it suits
Backpackers and cold weather campers who will protect the bag from moisture. Pair it with a snug shape for the most warmth; see mummy bags vs envelope bags.
Synthetic sleeping bags
Synthetic bags use polyester fibers designed to mimic down’s loft. They’re less efficient but more tolerant of moisture and easier to care for.
Pros
- Keeps some insulating value when damp.
- Dries faster than down.
- Lower cost for the same temperature rating.
- Easy to machine wash and hypoallergenic.
Cons
- Heavier and bulkier for the same warmth.
- Loses loft faster with years of stuffing and compressing.
- Often a shorter useful life than a well kept down bag.
Who it suits
Car campers, families, paddlers, and anyone camping in wet regions like the Pacific Northwest. Our Washington and Oregon camping guides cover areas where rain is common for much of the year.
How to choose
By trip type
On backpacking trips, down’s lighter weight and small packed size make a real difference. For car camping, weight and size barely matter, so a synthetic bag can save money without much downside. For canoe or kayak trips, synthetic handles splashes and humidity better, though any bag should ride in a dry bag.
By season
Summer bags don’t need much insulation, so the weight gap between down and synthetic is small. For spring, fall, and winter, down’s warmth for its weight matters more. In cold, dry climates like high mountains, down performs very well. In wet, cool conditions around freezing, synthetic is more forgiving.
By budget
Synthetic costs less upfront. Down costs more but can last longer with care, which narrows the gap over many years. If you’re new to camping, a synthetic bag is a sensible first bag.
Features worth checking
Beyond the insulation, look at the details that keep heat in. A draft collar around the neck and a draft tube along the zipper block cold air on chilly nights. A shaped hood and a roomy footbox add comfort. Water resistant shell fabric helps protect down from tent condensation, and a snag resistant zipper saves frustration at 2 a.m. Check the bag’s length too; a bag that’s too short compresses the insulation at your head and feet, and one that’s far too long leaves extra space to heat.
Ratings and pads
Compare bags tested to the ISO 23537 standard and choose by the comfort rating, not the lower limit. Use an insulated pad; no bag keeps you warm if the cold ground pulls heat away. Pad insulation is measured by R value, and higher numbers work better in cold weather.
Staying safe in the cold
Wet insulation and cold nights raise the risk of hypothermia. Change into dry clothes before bed, eat something, and keep your bag dry. Never use a fuel stove or heater inside a closed tent; carbon monoxide can build up and kill.
Care and maintenance
- Store both types loose in a large storage sack or hang them in a closet, never compressed in a stuff sack.
- Use a liner to reduce washing.
- Air out your bag every morning to release body moisture.
- Wash in a front loading machine with a cleaner made for down or synthetic insulation.
- Dry on low heat. Down can take several cycles; add dryer balls to break up clumps and make sure no damp spots remain.
- In camp, keep the bag in a waterproof stuff sack or pack liner.
Sleeping bag checklist
- Insulation type matched to your climate and trip
- Comfort rating at or below expected lows
- Sleeping pad with enough R value
- Waterproof stuff sack or pack liner
- Dry base layers and socks for sleeping
- Large storage sack for home
A good bag works best inside the right shelter. See ultralight tents vs family tents and how to choose the right tent.
FAQ
Is down warmer than synthetic?
For the same weight, yes. Two bags with the same comfort rating should feel similarly warm, but the down bag will usually be lighter and pack smaller.
What is fill power?
Fill power measures how much space an ounce of down fills. Higher fill power means more loft per ounce, so less down is needed for the same warmth.
Is water resistant down worth it?
Treated down resists moisture better than untreated down and can help in humid conditions, but it isn’t waterproof. You still need to keep it dry.
How long does a sleeping bag last?
It depends on use and care. Down bags stored loose and cleaned properly often outlast synthetic bags.
Shop the gear
Compare down and synthetic bags, pads, and liners in our sleeping gear section. For shelters that keep your bag dry, see our tents.
