The Best Summer Sleeping Bags for Backpacking in 2021

Therm-a-Rest Space Cowboy 45

Therm-a-Rest Space Cowboy 45

It is important to have good sleeping equipment on backpacking trips because it keeps you warm and comfortable during the nights. A sleeping bag is the most important piece of sleeping equipment; if you use a low-quality sleeping bag, your nights outdoor will not be comfortable even if you are using other sleeping equipment (sleeping pad, tent etc.) of the highest quality. A sleeping bag traps the body-warmed air and thus keeps you warm throughout the night. In summer when the temperatures are high, you can use a thin summer sleeping bag because it will provide enough warmth for the season. Summer sleeping bags are typically also lighter and less expensive than more insulated 3-season sleeping bags or winter sleeping bags.

In this review we selected the best summer sleeping bags to make your buying decision a little easier. We only listed lightweight summer sleeping bags which come for a great price. Please note that these sleeping bags are only suitable for summer use at low or mid altitudes (they provide enough warmth for temperatures down to 35° F (1° C).

If you are looking for a warmer sleeping bag, check out our review of the Best Down Sleeping Bags instead.

We regularly update our reviews and selections to always recommend you the best products on the market.

1. Buying a Summer Sleeping Bag for Backpacking – What is important?

Insulation:

Sleeping bags utilize either synthetic or down insulation. Down sleeping bags have a better weight-to-warmth ratio and pack smaller than synthetic sleeping bags. However, down sleeping bags also have downsides; they quickly lose their insulation if they get exposed to moisture and are quite pricey.

Summer sleeping bags typically utilize synthetic insulation because they are in general very light and pack small (they use less insulation material than for example 3-season sleeping bags) and thus it does not make sense to use expensive down insulation in summer sleeping bags.

Synthetic insulation is made of polyester fibers that mimic down clusters. Synthetic insulations differ in quality – a high-quality synthetic insulation can have similar heat-retaining properties as 650 fill power down. Polyester absorbs very little moisture (only “up” to 0.4% of its own weight) and therefore synthetic insulation retains warmth even if it gets wet or exposed to moisture.

Weight:

Summer sleeping bags are in general light because they require less insulation material than sleeping bags for lower temperatures. The weight of a sleeping bag depends on the quality of its insulation (warmth-to-weight ratio) and the amount of it. If a low-quality insulation is used, more of it is required for the same warmth. In this review of the best summer sleeping bags we only listed lightweight products.

Outer Material:

The outer layer of the sleeping bag should provide protection against abrasion and repel water, so the sleeping bag does not get wet if exposed to moisture/rain. The outer layer should be also breathable to prevent condensation from building-up on the inside.

Size:

Sleeping bags usually come in two sizes (Regular and Long). You should generally go for size L if you are taller than 6 ft. (180 cm). However, always check the sizing before making a purchase.

Temperature Rating:

Sleeping bag manufacturers usually list temperature ratings by the EN 13537 standard which means that their products went through a standard (and independent) laboratory test where it was determined for which temperature range they are suitable. The EN 13537 standard has four different ratings; extreme temperature (the average woman will survive), lower limit (the average man will be comfortable), comfort temperature (the average women will be comfortable) and maximum temperature (overheating limit).

Sometimes manufacturers use their own tests instead of the EN 13537 test. However, these tests tend to be inaccurate. In this review we only listed summer sleeping bags that were subject to the EN 13537 test.

Style:

There are several different styles of sleeping bags; mummy, quilt, wearable and envelope. In this review we only listed mummy sleeping bags because this type of sleeping bags offers the best versatility.

Expert Selections
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2. The Best Summer Sleeping Bags for Backpacking Review

Best Summer Sleeping Bags

Best Summer Sleeping Bags

The Best Summer Sleeping Bags for Backpacking – List

  1. Marmot NanoWave 55
  2. Nemo Forte 35
  3. Kelty Tuck 40
  4. Big Agnes Lost Dog 45
  5. Therm-a-Rest Space Cowboy 45

Comparison:

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Feature/Product Marmot NanoWave 55Nemo Forte 35Kelty Tuck 40Big Agnes Lost Dog 45Therm-a-Rest Space Cowboy 45
Weight1 lb. 8 oz. (regular size)2 lbs. 2 oz. (regular size - men's)3 lbs. (regular size)1 lb. 12 oz. (regular size)1 lb. 4 oz. (regular size)
Weight (Metric)680 g (regular size)960 g (regular size - men's)1350 g (regular size)794 g (regular size)570 g (regular size)
InsulationSpiraFilPrimaLoft RISEThermaProFireLine EcoEraLoft 120 3D Hollow Polyester
Outer MaterialNylon 30D Ripstop Nylon 75D PolyesterNylon Ripstop with DWR20D Polyster Ripstop with DWR
EN Lower Limit Rating55° F31° F40° F45° F45° F
EN Lower Limit Rating (Metric)12° C-1° C4° C7° C7° C
EN Comfort Temperature Rating60° F35° Fn/an/a52° F
EN Comfort Temperature Rating (Metric)16° C2° Cn/an/a11° C
Marmot Nanowave 55

Marmot Nanowave 55

1. Marmot NanoWave 55

Suitable for:

  • Hiking
  • Mountaineering (low and mid altitudes)
  • Backpacking
  • Camping
  • Cycling

The Marmot NanoWave 55 is an inexpensive summer sleeping bag which is perfect for occasional adventures in high temperatures. It is even lighter than the Millet sleeping bag mentioned above but on the other hand it is also less warm. The Marmot NanoWave 55 sleeping bag features a nylon outer layer and an inner layer made of a comfortable polyester fabric. The SpiraFil insulation is between these two layers. SpiraFil insulation was developed by Marmot and uses a blend of large spiral hollow fibers and small polyester fibers. This creates good loft and thus the sleeping bag efficiently retains warmth. The Marmot sleeping bag is equipped with a full-length two-way zipper, hood drawcord and two hang loops for drying. Due to its low price, the Marmot NanoWave 55 sleeping bag is perfect for those who are new to backpacking.

 

Pros:

  • Price
  • Comfort

Cons:

  • Weight
  • Warmth

 

Nemo Forte 35

Nemo Forte 35

2. Nemo Forte 35

Suitable for:

  • Hiking
  • Mountaineering (low and mid altitudes)
  • Backpacking
  • Camping
  • Cycling

 

The Nemo Forte 35 sleeping bag is available in regular and long versions for men and women respectively, and will keep you warm as long as the temperatures don’t go below the freezing point. It is a more sustainable choice than the cheaper alternatives on this list as it is insulated with PrimaLoft RISE, which is lightweight, ultra-lofty and durable while being made of 80% post-consumer recycled content. Like the rest of the Forte Line, the Nemo Forte 35 sleeping bag features the Spoon Shape design, so you can sleep comfortably on the side (which 70% of us do) and not just flat on your back. For temperature regulation, there is a Blanket Fold external draft collar and a full-length draft tube as well as Thermo Gills on the upper part which allow you to vent on warmer summer nights without letting in cold drafts.

 

Pros:

  • High-quality and sustainable PrimaLoft RISE insulation
  • Ventilation options make it suitable for a wider ranger of temperatures
  • Designed so you can sleep comfortably on the side
  • Integrated pillow pocket can be stuffed with clothing

Cons:

  • /

Video

Kelty Tuck 40

Kelty Tuck 40

3. Kelty Tuck 40

Suitable for:

  • Hiking
  • Mountaineering (low and mid altitudes)
  • Backpacking
  • Camping
  • Cycling

The Kelty Tuck 40 summer sleeping bag is with the weight of 1 lb. 8 oz. one of the lightest sleeping bags in this selection. The sleeping bag has a temperature rating of 40° F and utilizes the ThermaPro synthetic insulation which retains warmth even if it gets exposed to moisture. The shell and inner layers are made of 75-denier polyester. The sleeping bag has also a hood, natural fit footbox, media pocket and a zipper draft tube. It comes with a stuff sack and when packed it measures only 8 x 14 inches. The Kelty Tuck 40 is a great option for those who need a budget sleeping bag for their summer adventures.

 

Video

Big Agnes Lost Dog 45

Big Agnes Lost Dog 45

4. Big Agnes Lost Dog 45

Suitable for:

  • Hiking
  • Mountaineering (low and mid altitudes)
  • Backpacking
  • Camping
  • Cycling

 

The Big Agnes Lost Dog 45 is a very light summer sleeping bag (it weighs merely 1 pound and 12 ounces) with a great warmth-to-weight ratio. Like the Nemo Forte, it features a high-quality sustainable synthetic insulation – in this case the FireLine™ ECO insulation which is made of 100% post-consumer recycled polyester. The low denier fibers are tightly woven together which provides a high loft, compressibility and durability besides the warmth-to-weight ratio. Design-wise, the Big Agnes Lost Dog 45 is equipped with the Pillow Barn feature that keeps your pillow (or conveniently folded clothes) in place all night and the stretchy Flex Pad Sleeve on the back which means that you can connect it to multiple pad widths (rectangular shape required). The only “down side” for some might be that the regular size only accommodates people as high as 5’10’’ (178 cm); those who are taller need size Large or Wide Large.

 

Pros:

  • High-quality and sustainable FireLine™ ECO insulation
  • Nylon Ripstop shell fabric with DWR-treatment
  • Flex Pad Sleeve accommodates different pad widths

Cons:

  • Regular size is a bit shorter than other brands’

 

Therm-a-Rest Space Cowboy 45

Therm-a-Rest Space Cowboy 45

5. Therm-a-Rest 45

Suitable for:

  • Hiking
  • Mountaineering (low and mid altitudes)
  • Backpacking
  • Camping
  • Cycling

The Therm-a-Rest Space Cowboy 45 has the same temperature rating as the Big Agnes sleeping bag above, but is even lighter although the regular size still accommodates persons up to 6 feet tall (183 cm). Unlike the other summer sleeping bags on this list, the Therm-a-Rest Space Cowboy 45 is also available in a size small which fits people with a height up to 5’6’’ (168 cm) besides the usual regular and long version. The sleeping bag is insulated with Therm-a-Rest’s own eraLoft, which is made of water-resistant polyester that retains warmth when wet and dries fast. The insulation has been placed strategically (65% on top and 35% on the bottom) to keep the weight down without sacrificing warmth. The Therm-a-Rest Space Cowboy 45 is also equipped with removeable SynergyLink Connectors for attaching it to a sleeping pad, and blanket/quilt loops which allows you to combine it with other sleep covers, thus making it suitable for a wider range of temperatures.

 

Pros:

  • Good insulation with hollow-core fibers trap heat efficiently and offer excellent loft
  • Small size available for the petite
  • Zoned insulation to keep it lightweight
  • Design features to combine it with other sleeping gear

Cons:

  • Price

Video

 

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Author Information

Blaz

Outdoor enthusiast with experience in all types of hiking and mountaineering. Hiked in the Alps, Iceland and other countries. In love with via ferrata trails and snow-covered slopes. Check out my hikes.