Therm-a-Rest Questar 20°F Sleeping Bag
The Therm-a-Rest Questar 20 delivers dependable warmth for backpacking trips across spring, summer, and fall. We built this bag with 650-fill Nikwax Hydrophobic Down that resists moisture and maintains loft even in damp conditions. The SynergyLink™ Connectors integrate with your sleeping pad to eliminate cold spots and keep you centered through the night.
Our streamlined mummy design reduces weight without sacrificing comfort. The zoned insulation places more down where you need it most — across your core and feet — while reducing bulk in areas that don't require maximum warmth. Whether you're logging miles on the trail or setting up camp above treeline, the Questar 20 packs small and performs when temperatures drop.
What makes the Questar 20 stand out
Hydrophobic down insulation technology
We treat every down cluster with Nikwax Hydrophobic technology to create a moisture barrier at the molecular level. Traditional untreated down loses loft and insulating power when exposed to humidity or condensation inside your tent. Our hydrophobic treatment allows the down to dry faster and retain warmth even when damp.
The 650-fill power rating strikes a balance between packability and thermal efficiency. Higher fill powers offer marginal weight savings but at a significant cost increase. We selected 650-fill because it delivers the performance most backpackers need without the premium price tag of 800+ fill down bags.
SynergyLink pad attachment system
The SynergyLink™ Connectors are integrated loops that snap directly onto compatible Therm-a-Rest sleeping pads. This system prevents the bag from sliding off your pad during the night and eliminates the cold air gaps that form when you shift position. You stay centered on your insulation all night instead of waking up on the tent floor.
Even if you don’t use the connectors, the system adds negligible weight. The loops sit flat against the bag and don’t interfere with the zipper or interior space. For winter camping or colder conditions, backpackers sometimes layer the Questar 20 with a Hyperion 20 or similar lightweight bag to extend the temperature range without carrying a dedicated winter bag.
Sizing and fit details
Mummy taper and shoulder girth
The Questar 20 uses a classic mummy profile that tapers from shoulders to feet. Regular size offers 62 inches of shoulder girth and 40 inches at the hips. The taper reduces excess fabric and dead air space you’d otherwise have to heat with your body. Side sleepers and those who shift positions frequently still have enough room to move without feeling constrained.
Toe-asis™ Foot Box
Our Toe-asis™ design adds extra volume in the foot box so your toes rest in a natural position instead of being compressed against the end of the bag. Compressed insulation loses loft, and many backpackers experience cold feet simply because their bag’s foot box is too tight. The added space also accommodates thicker camp socks without further compression.
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Common questions about the Questar 20
The Questar 20 has an EN Lower Limit rating of 20°F, which represents the temperature at which a standard cold sleeper remains comfortable. Most backpackers find it works well down to about 25°F without adding layers. Cold sleepers or those camping in windy exposed areas may want to add a liner or wear thermal layers when temps approach 20°F. For summer trips where overnight lows stay above 40°F, this bag will be warmer than necessary.
The Parsec 20 offers more interior space with its semi-rectangular shape, making it better for car camping when weight isn't a concern. The Questar 20 uses a tapered mummy design that's lighter and packs smaller, ideal for backpacking. Both share the same temperature rating and hydrophobic down treatment. If you primarily car camp and value room to move, the Parsec is the better choice. For backcountry trips where every ounce counts, stick with the Questar.
You can safely wash the Questar 20 at home in a front-loading machine. Use a technical down wash and avoid regular detergent, which strips the hydrophobic treatment. Dry it on low heat with dryer balls, checking periodically to break up clumps. The process takes 2-3 hours but saves the cost of professional cleaning. We recommend washing only when necessary — typically once per season or after 20-30 nights of use.
The SynergyLink™ Connectors are designed for Therm-a-Rest pads but the bag works fine with any pad if you don't use the attachment system. The connectors simply remain tucked away and don't interfere with normal use. You lose the anti-slip benefit, but the bag's draft collar and zipper baffles still prevent heat loss. Many backpackers use the Questar successfully with pads from other manufacturers.
Every Questar 20 ships with a compression stuff sack for trail use and a larger mesh storage sack for home storage. The stuff sack compresses the bag to roughly 8 x 16 inches. The storage sack is oversized to prevent long-term compression that damages down loft. Both sacks are included in the listed price with no additional purchase required.
Nikwax Hydrophobic Down treatment is applied during manufacturing and is designed to last the lifetime of the bag with proper care. Unlike spray-on treatments that wear off, the hydrophobic coating bonds to individual down clusters. Washing with technical down wash preserves the treatment. Avoid using regular detergent or fabric softener, which can degrade the moisture resistance over time.
The 20°F rating makes the Questar best suited for 3-season use — spring through fall in most regions. For dedicated winter camping when temps drop below 15°F, consider the Questar 0 or adding a sleeping bag liner to extend the temperature range. Some experienced winter campers layer two bags for flexibility, but a purpose-built winter bag is generally more efficient for sustained cold weather trips.