Gear

Synthetic sleeping bag

Synthetic three-season sleeping bag.

Sleeping bags with synthetic-fibre fill. Heavier and bulkier than down, but cheaper, more hard-wearing and far better at keeping their insulating ability when wet.

Sleeping bags with synthetic fill are generally cheaper than down bags. They are also considerably heavier and have a larger packed volume — but they have three big advantages:

  • Cope with damp — they keep around 50% more of their insulating ability when wet compared with down.
  • Hard-wearing — if you get a hole, the fill does not come out the way it does with down.
  • Ethical questions around down production are not an issue.

The synthetic fibres keep their loft even when wet, so the layer of air is held in place — and it is the air that insulates.

When does it suit?

  • Trips in damp conditions (the coast, autumn trips, rain)
  • Longer trips where you cannot dry the bag between stages
  • A limited budget — good warmth for the money
  • You prioritise durability over packed volume

When does it suit poorly?

On demanding mountain trips or expeditions where every gram and every litre of pack space counts — there, down is superior.

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