Sea to Summit Spark Women’s Review 2024 Edition
For a sleeping bag designed to accommodate cold sleepers and curvier bodies, choose the Sea to Summit Spark Women’s edition, updated for 2024 and previously referred to as “Flame.” This bag is ~40% warmer (and bulkier) than S2S’s unisex model of the same temperature rating, and in unisex rating terms, could have been called a 5F. It’s a great lightweight sleep system with high quality down fill and shell fabric, an exceptional warmth-to-weight ratio, and is the overall best women’s specific model on the market. Shop now.
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Sea to Summit Spark Women’s 15 Key Stats
- Price: $549
- Weight: 32.8 oz
- Down: 850 fill power RDS Ultra Dry down
- Fill Weight: 24.2 oz
- Fabric: 10D nylon
- Down Vol: 20570 in³ | Down Vol/oz: 627 in³
- Estimated Comfort: +15F for cold sleepers, +5F for warm sleepers
- Pros: Minimalist feature set. Exceptional warmth-to-weight ratio. Very warm. Conservative temp rating. High quality materials.
- Cons: Expensive. Bulky. Somewhere between lightweight & midweight.
Compare to more great options in our guide to the best sleeping bag for backpacking.
Construction & Features
Physiologically speaking, women sleep slightly colder than men, which is why the Sea to Summit Spark Women’s sleeping bag is approximately 40% warmer than the unisex version of the same temperature rating. Comparing 15F rated bags, the W’s version has 20k in³ total down insulation volume, while the unisex has 14k. While 850 fill power down is overall high quality and compresses nicely, you can only do so much to minimize bulk.
This bag is also designed to fit women’s bodies. As such, Sea to Summit has widened the hips, narrowed the shoulders, and shortened the length. That beings said, it’s not drastically different from the unisex cut and we don’t see why a colder sleeper man couldn’t also use the w’s version.
Beyond the shape and increased down fill, Sea to Summit Spark Women’s is the same great bag as the unisex. We appreciate the use of 10d nylon shell fabric, which saves weight while still offering sufficient durability and comfort. Many mainstream outdoor brands of comparable size to Sea to Summit shy away from thinner shell fabrics, instead opting for 15d or 20d, and thus catering to the lowest common denominator who are more likely to damage their bag. Not so here.
There’s lots of little design touches that make this a great sleeping bag. We nod to the mixed baffles orientation which prevents down drift and cold spots, especially for side sleepers. Also the draft tube, and zipper plow, which seems to never get stuck. Lastly, its zippers can mate with the unisex version to make a cozy 2P hybrid bag.
Spark vs Spark Pro vs Spark Women’s
In summary:
- Spark Pro is the best all around due its use of 950 FP down and generous fill quantity at all temp rating gradations, but also the most expensive and we aren’t impressed by the zippers and quilt conversion
- Spark W’s is the warmest, but also heaviest and bulkiest at each temperature rating gradation. Because you get more down fill for the same price as the unisex Spark, it is a better value. It also claims the highest warmth-to-weight ratio
- Spark Unisex is a good all-around blend of high performance, low weight, and low bulk, but not the best on any one measurement and has the lowest warmth-to-weight ratio
- Ember Quilt is the lightest weight, lowest bulk and best value, just remove the under-pad strap system3
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| Sleeping Bag | Price ($) | Weight (oz) | Fill Power (in³) | Fill Weight (oz) | Down Volume (in³) | Down Vol/Total Weight (in³/oz) |
| Spark W 15 | 549 | 32.8 | 850 | 24.2 | 20570 | 627 |
| Spark Pro 15 | 649 | 27.7 | 950 | 16.9 | 16055 | 580 |
| Spark 15 | 549 | 25.7 | 850 | 16.9 | 14365 | 559 |
| Spark W 30 | 449 | 20.6 | 850 | 13.2 | 11220 | 545 |
| Ember 30 | 399 | 19.2 | 850 | 12.3 | 10455 | 545 |
| Spark Pro 30 | 549 | 21.8 | 950 | 10.9 | 10355 | 475 |
| Spark 30* | 449 | 17.4 | 850 | 9.3 | 7905 | 454 |
Table sorted by warmth-to-weight ratio using the Down Vol/Total Weight (in³/oz) stat as closest approximation
- *Spark 30 unisex is underfilled relative to its rating, has the lowest warmth-to-weight ratio, and will feel more like a 35F bag
Sea to Summit Spark Women’s Review 2024 Verdict
Cold sleepers will love the Sea to Summit Spark Women’s sleeping bag, which is temp rated extremely conservatively – it has enough insulation to justify a unisex 5F rating. The 850 power down is great-not excellent, and the 10d nylon shell is truly ultralight. All in all, this is a killer sleeping bag with an exceptional warmth to weight ratio and perfectly suited to cold sleepers. Our pick for best women’s specific model on the market.
