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Down vs synthetic sleeping bag for cold weather camping

Down vs synthetic sleeping bag for cold weather camping: down packs smaller and lighter, synthetic copes better with damp and is easier to care for.

Karim Belkacem4 min read

Two rolled sleeping bags of different sizes on the floor of a tent
Photo by cottonbro studio on Pexels

Verdict: pick down if you want a light, small, warm bag and you will keep it dry. Pick synthetic if your trips are damp, if you want easy care or if the bag will take rough use. Both can keep you warm. They fail in different ways.

Which wins on

FactorDownSynthetic
Warmth for weightBetterLower
Packed sizeSmallerBigger
When dampLoses loft and warmthKeeps more warmth
Dry timeSlowFaster
CareNeeds special washing and dryingEasier
Long-term loftLasts well with careLoses loft sooner
Treated or untreatedSome are water-resistant treated downFills vary

Down is the soft layer from ducks or geese. Synthetic is man-made fibers. Both trap warm air.

Pick down if

  • You hike or backpack and every gram counts.
  • You camp in cold, dry air.
  • You have space to store the bag loose at home.
  • You can keep it dry, with a dry sack and a good tent.

Down fill is rated by a number called fill power. Higher numbers mean more loft per weight. The maker's page lists it.

Pick synthetic if

  • You camp in humid, wet or snowy places.
  • You mostly car camp and weight does not matter.
  • You want something simple to wash.
  • You camp with kids, who may spill things or drag the bag.

What goes wrong first. With down, it is moisture. Breath and sweat make the fill clump, and a wet bag loses its warmth. With synthetic, it is bulk and age. The fill flattens and the bag gets heavier to carry.

A down sleeping bag lofted fully on a tent floor
Let a down bag fluff up before you get inImage by cuncon from Pixabay

Rule that matters most

Dry is warmer than any fill. Whichever bag you pick, keep it in a dry bag in the pack and air it at the camp. If you expect lots of wet, buy synthetic. Otherwise choose on weight and size.

Do not forget the pad

A bag cannot insulate under you because your weight crushes it. A pad does that. See sleeping pad R-value for cold weather camping. To read the numbers on the bag, use sleeping bag temperature rating explained.

How to care for each

Good care keeps either bag warm for years.

Down: - Store it loose in a large bag, not squashed in the stuff sack. - Wash it rarely, using a wash made for down, on a gentle cycle. - Dry it slowly on low heat, and fluff it often, until fully dry. - Air it each morning on a trip.

Synthetic: - Store it loose too, to stop the fill from flattening. - Wash it as the label says, usually in a front-loading machine. - It dries faster, but still needs time.

Always check the maker's care label. A bag that is stored compressed for long periods loses loft, whatever the fill.

Which one for which trip

TripBetter fit
Dry mountain backpackingDown
Wet, mild climateSynthetic
Car camping with kidsSynthetic
Long winter tripDown, kept dry in a dry bag
Trips where bags get wetSynthetic

If you are unsure, start with synthetic. It forgives mistakes. Switch to down when weight starts to matter.

Quick questions

Is down always warmer than synthetic?

Not always. It is warmer for its weight. A big synthetic bag can be very warm, but heavy.

Can I wash a down bag at home?

Many can be washed with a down wash and dried well on low heat. Follow the maker's care label.

Which is better for kids?

Synthetic is usually easier to care for. See kids sleeping bag vs adult sleeping bag.

Does a liner help?

A liner adds a small amount of warmth and keeps the bag cleaner.

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