Amplitude Down Sleeping Bag (-4°C & -15°C)
BEST USE: Car Camping
PERFORMANCE: 3.5 Season
WEIGHT: 3lbs 1.2oz | 1395g
COMPRESSED VOLUME: 10.4 liters
Shipping & Returns
We want you to have the best possible experience when using our website which is why we offer free shipping on orders over £50 and £3.95 for orders under this.
We aim to dispatch your order on the same day and deliver it the following working day For more details, check out our Shipping Policy.
We also offer a free-of-charge return service meaning you can buy in complete confidence from us. For more details, please check out our Refund Policy.
Ideal for adventures with a base camp, the Amplitude down sleeping bag brings spacious luxury and incredibly versatile ventilation options to wherever your travels may take you. Each side of the Amplitude has a full-length side zipper; a third zipper can be found in the foot box.
High-lofting down and quality construction keeps you cosy when it's cold, and the zippers provide temperature regulation up to the point where you remove the upper section and sleep under it as a quilt.
The only thing which might be cosier would be a double version - and we have that, too.
Best UseCar Camping
Comes WithUltra-Sil Compression Sack
InsulationUltra-Dry Down 750+ Loft
Shell Fabric30D Nylon shell
Zip OptionsFull length left side, right side and foot box zipper. This provides more options than we have room to list.
|Regular Amplitude II (-4°C)
|Regular Amplitude III (-15°C)
|Long Amplitude II (-4°C)
|Long Amplitude III (-15°C)
The second highest-lofting down used in any of Sea to Summit’s sleeping bags. 750+ Fill Power indicates that one ounce (30g) of down will re-expand to over 750 cubic inches after compression. Higher loft means that less down can be used to achieve the same temperature rating – important for performance sleeping bags. The loft and down quality/composition are independently tested by the International Down and Feather Laboratory (IDFL) – a copy of the certification is supplied with every Sea to Summit sleeping bag. The down is responsibly sourced and RDS certified and treated with the environmentally-friendly Ultra-Dry Down treatment.
100% of the down used in our sleeping bags and quilts is independently certified to the Responsible Down Standard (RDS). The RDS certifies down against animal welfare requirements and tracks it from the source to the final product. The purchase of RDS certified products demonstrates demand for better animal welfare practices in the down and feather supply chain. Sea to Summit is certified to the RDS. To learn more about RDS visit
Down and synthetic bags identified with our zip coupling symbol use a 65 inch #5 YKK full-length zip which allows a unisex left-handed and women's specific right-handed bag to pair together. Designed to pair side by side, each person sleeps in their own bag enabling each of you to take advantage of your bag's unique insulation zones, hood and footbox features - perfect for cozy adventures for two. Bags with full-length #5 YKK zips on both sides can also be coupled together with other pairing bags.
Frequently Asked questions
Warm enough for cool weather camping or travel?
Yes. The quality down and technical construction keeps you warm even on chilly nights. We recommend the Amplitude -15°C paired with a greater than 3.5 R-Value sleeping mat, like the Comfort Plus Insulated. This pairing will keep you warm through shoulder seasons.
Suitable for summer temperatures?
Yes. The full-length side zippers and foot box zipper can be opened for ventilation or remove the upper section completely for use as a comforter.
Fitted with a sleeve to slide in a sleeping mat?
No - instead the lower part of the Amplitude is fully insulated to avoid cold spots – elasticated straps on the underside attach to a sleeping pad of your choice to form a roomy, cozy sleep system.