Skip to main content

NEMO Sonic Down Sleeping Bag (-18C)

NEMO Sonic Down Sleeping Bag (-18C)
Please select options


Sonic is built to be the only bag you need from -20°F to 40°F. The Backpacker Editors’ Choice award-winning big-mountain bag offers exceptional warmth and tuneability with a reduced environmental impact. This bag features our next-generation Thermo Gill™ vents, with a new multistage zipper system that dramatically increases the usable temperature range of the bag and allows fine-tuning of comfort from within. Sonic’s chevron baffle construction better compartmentalizes down, eliminating migration and keeping the down evenly lofted. (Not to mention, it looks awesome.)

The shell and liner fabrics are 100% recycled fabrics and bluesign® approved, and the premium 800 FP hydrophobic down is 100% Responsible Down Standard (RDS) certified.

Years of history in the field yielded detailed upgrades on this bag, including a perfected profile, redesigned draft collar, and bolstered draft tubes.

The proven Nemo Toester™ footbox keeps feet warmer, provides a waterproof barrier against tent wall condensation, and protects down from moisture while drying damp clothes inside the footbox.
Adaptable to whatever the mountain throws at it, Sonic continues to reverberate as the ultimate extreme weather companion.

Bag Type: Mummy
Bag Weight: 1.47kg / 3.25lbs
Fill: 800 FP PFC-Free, RDS certified hydrophobic down?
Fill Weight: 790g / 1.75lbs
Compressed Volume: 9.6L

Award-winning design?is updated for even greater warmth retention and adjustability across temperatures.

Updated design incorporates 100% recycled, bluesign® approved shell and liner fabrics.

Updated?Thermo Gills™?extend the comfort range with a new multistage zipper system.

Overstuffed with?premium 800 FP hydrophobic down?that is PFC-Free and 100%?Responsible Down Standard (RDS) certified, ensuring humane treatment and traceability throughout the supply chain.

New chevron baffle construction better compartmentalizes down for more uniform loft and down migration prevention.

Stretch construction?at the knees for comfortable side sleeping.

Redesigned draft collar?and?draft tubes keep cold air out.

Redesigned?Toester™ waterproof/breathable footbox?utilizes a layer of synthetic insulation to protect the down and deliver maximum toastiness for toes.

Offset zipper?creates a thermally efficient seal while an updated profile?secures warmth closer to the body.

Protected by the?NEMO Lifetime Warranty.

Includes Compression sack and mesh storage bag

Minimum Weight Short - 3 lb , 2 oz / 1.42 kg
Regular - 3 lb , 4 oz / 1.47 kg
Long - 3 lb , 9 oz / 1.62 kg
Packed Size Short - 13.0 x 9.5 in / 33 x 24 cm
Regular - 13.5 x 9.5 in / 34 x 24 cm
Long - 14.0 x 9.5 in / 36 x 24 cm
Fill Type 800 FP Down
Fill Weight Short - 1 lb , 11 oz / 770 g
Regular - 1 lb , 12 oz / 790 g
Long - 1 lb , 13 oz / 835 g
Fits Up To Short - 5'6" / 168 cm
Regular - 6' / 183 cm
Long - 6'6" / 198 cm
Shoulder Girth Short - 61 in / 155 cm
Regular - 63 in / 160 cm
Long - 65 in / 165 cm
Hip Girth Short - 56 in / 142 cm
Regular - 58 in / 147 cm
Long - 60 in / 153 cm
Knee Girth Short - 51 in / 130 cm
Regular - 53 in / 135 cm
Long - 55 in / 140 cm
Compressed Volume Short - 8.9 L
Regular - 9.6 L
Long - 9.9L
Shell Fabric 100% Recycled Nylon, Bluesign Certified
Footbox Fabric 100% Recycled Nylon, Bluesign Certified
Lining Fabric 100% Recycled Polyester, Bluesign Certified
Zipper Location Left

Tips for Taking Care of your Sleeping Bag

Store your sleeping bag in an oversized breathable sack when not in use. Tightly compressing your sleeping bag for long periods of time can damage the down/synthetic insulation over time, causing a loss of loft and potentially affecting the warmth retention capabilities of your sleeping bag. Only compress your bag when necessary for backpacking or transportation purposes. When you get to camp, make sure to decompress your bag by leaving it unrolled and flat for a few hours (or as much time as you can) before using it — this will enable the down to loft back up and create a nice, puffy effect for a cozy sleep when you’re ready for bed!

Keep your sleeping bag clean. Oil and dirt can greatly affect a sleeping bag’s insulation over time. We know it’s hard to stay clean in the backcountry, especially after a summer day of hiking. When possible, give yourself a quick wash with a wet cloth and wear clean clothes to bed. Going to bed semi-clean feels so much better and in the long run, it’ll help your sleeping bag too.

Spot clean when possible, wash when needed. Your sleeping bag is composed of lightweight materials and delicate insulations — washing your sleeping bag after every trip is not recommended because the harshness of soaps and water can take a toll. When possible, only spot clean your sleeping bag. Use a non-detergent soap and make a paste with a small amount of water. Using a cloth or even a toothbrush, clean the affected area of your sleeping bag. Try not to get the insulation of the bag wet by pulling the fabric away from the insulation when cleaning.

Sometimes your bag is dirty, we get it. It means you’ve been on some great adventures! When you notice your sleeping bag looking flat, loss of loft, or generally pretty grimy — follow the directions below for washing. Washing your bag will definitely help revitalize the loft and warmth of your bag.


Washing your sleeping bag

If your sleeping bag is exposed to dirt, sand, etc., you can simply wipe it down with a wet cloth or spot clean with mild, non-detergent soap in cold water.

For excessive dirt and oil, we recommend the following steps:

Wash your sleeping bag on a gentle cycle with a two-rinse option in cold water in an oversized, front-loading commercial washing machine with no agitator.

Wash your sleeping bag with a technical fabric wash like Nikwax Tech Wash®.

Tumble dry low heat in an oversized commercial dryer. Add some clean tennis balls to the dryer to help thoroughly dry the down/synthetic in your bag. Expect your sleeping bag to take several hours to fully dry.

Once dry, shake your sleeping bag to restore the loft.

Other Notes: Do not use bleach on your sleeping bag. Do not dry a wet sleeping bag while it is bundled. Do not iron and do not dry clean. Do not use a high heat setting when drying your bag — this can melt the technical sleeping bag fabrics.


Cleaning Zippers

It is also important to keep the zippers of your sleeping bag clean. If your bag is exposed to dirt, sand, or salty air, wipe the zipper down with a wet cloth. In excessive cases, wash and treat zippers with a lubricant such as McNett Zip Care™ or a silicone zipper spray (popular in dive shops).


Sleeping Bag Storage

Taking care of your sleeping bag in the off-season is just as important as during the backpacking and camping season.

After each trip, follow these steps for keeping your sleeping bag in good condition for the next season:

Clean the sleeping bag using the washing directions above for excessive dirt and oil build-up. If your bag is relatively clean, let the bag air dry on a clothesline for at least 24 hours in low humidity weather conditions before storage.

Make sure your sleeping bag is completely dry before storing it. This is the most effective way to prevent mold and mildew from forming on your sleeping bag.

For long term storage, keep your sleeping bag in an oversized breathable storage sack or on a clothes hanger. Do not store your sleeping bag in its compression sack. Tightly compressing your down/synthetic sleeping bag can damage the insulation and loft of the bag.

Store the sleeping bag in a cool, dry, and dark area — away from direct exposure to sunlight.


Sleeping Bag Repairs

Small tears and rips can easily be patched with a product like Tenacious Tape™ by Gear Aid™. Just clean the area of the sleeping bag that needs patching, then peel and stick the patch on the tear. You’ll have a durable, nearly invisible repair that won’t leave behind a sticky residue as duct tape can.


NEMO | Sonic™ Down Sleeping Bag

Backpacker Editors’ Choice award-winning, Sonic™ has been updated for even greater warmth retention and adjustability from -20°F to 40°F. The updated design incorporates 100% Global Recycled Standard (GRS) recycled, bluesign® approved shell and liner fabrics. The redesigned?Toester™ waterproof/breathable footbox?utilizes a layer of synthetic insulation to protect the down and deliver maximum toastiness for toes. Adaptable to whatever the mountain throws at it, Sonic™ continues to reverberate as the ultimate extreme-weather companion.

Part Numbers

Option UPC MPN Store SKU
Short 811666034519 NemoSonic0short SLE35908142