Yeti Crystal Down

As stockists of Yeti Sleeping Bags, including the lightest Sleeping Bag in the world, the Fever Zero, here’s our explanation of what makes Yeti products so special: their incredible down.

Yeti use only the finest goose down, which alongside ultralight fabrics and construction methods makes Yeti Sleeping Bags the lightest, most compressible sleeping bags in the world. It is in recognition of the exceptional quality, purity, and traceability of this down that Yeti give it the name ‘Crystal Down’.

To illustrate the incredible air-trapping ability of Yeti Crystal Down, Yeti themselves cite that the total filling of a Yeti Passion One Down Sleeping Bag would compress into 60 thimbles; a volume of around 77ml. Remove the down from its theoretical thimbles and it will rapidly expand to its full volume once again unharmed. For information on what sets Crystal Down apart from other down, read on.

Yeti Crystal Down Testing

The quality and performance of Yeti Crystal Down is tested in labs run by the leading down testing and auditing body; the International Down and Feather Laboratory (IDFL), in Salt Lake City USA. Fill power (the measurement of loft) is tested using the Lorch cylinder test, which involves placing an ounce (30 grams) of down in a cylindrical flask, which is then pressurised by a ‘lid’ of a standard weight to compress the down. When the compression ceases, the volume of the down under pressure is measured in cubic inches. The higher the volume; the higher the loft of the down – and the higher its quality.

In the Lorch cylinder test Yeti Crystal Down achieves an incredibly high fill power of at least 850 cubic inches per ounce: 950 in the case of the Yeti Fever Zero Sleeping Bag (900 fill EU). In addition, all Yeti down is tested and certified for its down/feather ratio, achieving at least a 95/5 ratio of down/feathers, with some down fills exceeding a 97/3 ratio. This makes Crystal Down just about the purest down used anywhere in the outdoor industry.

The Crystal Down Supply Chain

The raw down that eventually becomes Yeti Crystal Down, is plucked from flocks of mature breeding geese in Masuria, Poland. Yeti trace all of their down back to its farm of origin, and only deal with farmers willing and able to proscribe to their code of conduct, the Yeti Ethical Code. This entails that geese are allowed to roam free, and plucked only after their slaughter for the meat industry to ensure that none are inhumanely caged or live-plucked.

Healthy, non-live-plucked mature geese produce very large high-quality down clusters, measuring around 4 cm in diameter. These provide extraordinary lofting power for the highest possible warmth to weight. Smaller, ‘Unripe’ down clusters on the other hand, gained during the moult of young animals or through live-plucking, are smaller, sharpener and likely to poke through the outer fabric of a sleeping bag. They also provide inferior loft and warmth for their weight. You won’t find down that fits this description in any Yeti product.More than 80% (soon to be 100%) of Yeti’s down sleeping bags are supplied with a code which details the loft of the down, its region of origin, slaughter operation, bird breed, and mixing ratio. 00RP1PWKG955 for example means: Down with minimum 800 fill power from the Pomerania region; farm operation 1 from a Polish White Koluda Goose; filling consists of 95 per cent down, five per cent feather according to European EN 12934 regulations.


The ‘raw’ goose down is sent to Germany, where a family business with 4 generations of experience in the down/feather industry washes it, heats it to kill microbes, and sorts it until the down/feather ratio has reached the required purity of at least 95% down, 5% feather. It is then sent to the Yeti factory, also in Germany, where it is inserted by hand into Yeti’s down sleeping bags. Yeti give one final note on their Crystal Down: even large, high quality down may occasionally poke through the outer fabric of a Yeti sleeping bag. Should you find an escapee down cluster, don’t panic! In order to  avoid the hole in the fabric becoming larger, don’t pull it out; try to pull it back into the sleeping bag from the inside. Then smooth over that area with your fingernail. This will stop further down clusters from escaping, keeping your Yeti Crystal Down sleeping bag in top condition. Down is by far nature’s finest insulator, but as Yeti say; “Nature is not completely controllable!”