Cumulus: The Lightest Down Sleeping Bags & Jackets in the World

Maria Weidich

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

When communism fell in Poland in 1989, and suddenly anyone could start their own business, Zdzislaw Wylezek did just that. He founded Cumulus, maker of the lightest down sleeping bags and jackets in the world, all sourced, stitched and stuffed locally in Poland.  

Zdzislaw’s son Jacek, who now runs the brand, remembers the business taking place largely in his family’s basement. At the time, raw materials were extremely scarce and “a high dose of creativity was often needed to get anything done,” he said.   

Finding those first customers in the new, free market era was uncharted territory. “It was an unknown land for every Polish citizen,” Jacek added. “And all of that without online sales!”

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

Today, Cumulus has a team of 36 people, and the brand also works with local sewing companies, all within a 40 minute drive from their headquarters, “which allows us to fully control all aspects of the manufacturing process,” Jacek said. 

Cumulus still hand-fills their sleeping bags themselves. Until 2011, Jacek explained that his dad insisted he fill the sleeping bags himself. Jacek had to convince him “that another person might do it properly as well, which wasn’t easy: neither the job nor the convincing.”

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

A bonus of calling Poland home is relatively easy access to Polish goose down. It’s the only down fill Cumulus uses, and according to Jacek, is considered to be the best down in the world.

“Being based in Poland, we have special relationships with the down producers who value our long-term business. We only use certified down and we can monitor the production so we are absolutely sure that it has been ethically sourced and comes from free-range geese that have access to water.”

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

Ultimately, the brand’s core value is to produce fast, light and reliable outdoor products.

“I believe that a continuous evolution of our products, which comes from direct feedback from our customers, differentiates us from others,” Jacek said. 

Jacek explained in the ’90s, simplicity was key for constructing Cumulus’ sleeping bags, and that still holds true today. “Only over time,” he added, “we’ve added useful functionalities or redesigned the cuts to more ergonomic ones.”

“The fabrics on the other hand, brought a true revolution in the weight,” he said. “This, along with some designing tricks, allowed us to create bags which we believe to be the lightest in the world.”

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

Jacek is proud of the Cumulus team and the reputation they’ve created, too.

“We encourage our employees to bring their own ideas about what’s working fine and what’s not,” Jacek said. “This is something I value the most: they understand that the company’s success is very dependent on their own actions and that we all co-create this path we’re marching on.”

“What is more, our team is made of people who love the outdoors and enjoy spending time in nature, so they always use and test our products,” he said. 

Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket

Today, as Cumulus’ popularity rises, they’re funneling some of that momentum toward larger causes. The brand joined 1% for the Planet helping environmental organizations tackle global issues. But donating money “is the easy thing,” Jacek said. “The hard thing is to start donating our time and actions for the cause of making our activities as eco-responsible as possible.”

“The good reputation carries along a lot of high expectations as well, so it gives us a drive to make it an even better workplace and evolve in the direction of being a company that stands for our values.” 


Cumulus UL Ultralight Best Lightest Down Sleeping Bag Jacket
Cumulus Sleeping Bags




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1 comment



Do not buy gear from cumulus equipment if you live in the USA. The return or exchange costs are prohibitive, over $200.00.

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