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Sea to Summit Flame Ultralight Women’s Sleeping Bag 48°F / 9°C review: a gentle hug in warm weather

An extra comfortable sleeping bag, the Sea to Summit Flame Ultralight Women’s Sleeping Bag is ideal for summer sleep-outs and camping adventures

Sea to Summit Flame Ultralight Women’s Sleeping Bag
(Image: © Sea to Summit)

Our Verdict

Made for summer, but intelligently designed to provide comfort and warmth where women need it most.


  • Ultra-packable
  • Super comfortable


  • Warm weather use only
  • Pricey

Sea to Summit Flame Ultralight Women’s Sleeping Bag: first Impressions

The female-specific Sea to Summit Flame Ultralight Women’s Sleeping Bag might be the most summer-focussed bag in this Sea to Summit range, but it’s still stuffed with more down than the men’s equivalent, and the fill is body-mapped to give women warmth where they need it.

It’s shorter than the men’s bag too, but is one of the few female-specific bags available where taller women can opt for a longer version. The Flame has a women’s specific cut that’s narrower at the shoulders and wider at the hips and knees.

The bag packs into Sea to Summit’s Ultra-Sil compression sack, which is as featherweight as the bag and when full is about half the size of a liter Nalgene bottle. A third-length zipper provides access.

For adventures in colder climes, the Flame Ultralight is also available in versions that will keep you comfortable at 2°C / 35°F, -4°C / 25°F, and -10°C / 15°F (see: Sleeping bag temperature ranges explained and How to choose a sleeping bag).


RRP: $319 (US) / £225 (UK)
Weight: Regular 350g / 12.3oz Long 395g / 13.9oz
Max user height: Regular 170cm / 5ft 7in Long 183cm / 6ft
Packsize: 2.5L to 1L
Fill: RDS-certified Ultra-Dry Down 850+ Loft
Comfort: 9°C / 48°F
Compatibility: 2-season camping adventures at low altitude

In the field

I found this to be the lightest, most compressible, easy-to-pack and delicious-to-sleep-in summer bag that I tested this pre-season (see: Best women’s sleeping bags).

For backpacking and bikepacking, I want a breathable, warm, quick-drying, and ultra-compact sleeping bag, and Sea to Summit’s FML is it. The Ultra-Dry Responsible Down Standard 850+ down was lofty, light, and warm. It’s treated to repel moisture, whether that’s sweat or condensation. So, the bag dried quickly in the morning and was ready to pack up so I could hit the road. Down didn’t poke through, even though the inside and outside shell are a super light, translucent 10D nylon that helped the bag to be superbly packable.

Cut narrower in the shoulders and wider in the hip than the men’s bag, on a bikepacking trip, the compressed bag was small enough to cram into a Jetboil cup. In my tent, with the Flame FML uncompressed and lofted, it was truly comfortable and warm.

This was my favorite summer bag, but I also used it as a liner inside another bag for fall and winter camping.