# Cosmic Down 20 Sleeping Bag vs UltraLite Sleeping Bag: specs and price compared

A sourced, side-by-side comparison of the Cosmic Down 20 Sleeping Bag (Kelty) and UltraLite Sleeping Bag (Western Mountaineering) among sleeping bags. Cosmic Down 20 Sleeping Bag is the cheaper of the two at $189.95.

## Side by side

| Spec | Cosmic Down 20 Sleeping Bag | UltraLite Sleeping Bag |
| --- | --- | --- |
| US price | $189.95 | $660 |
| Brand | Kelty | Western Mountaineering |
| Released | 2024 | — |
| Temperature rating f | 20 | 20 |
| Insulation type | down | down |
| Fill power | 550 | 850 |
| Shape | semi-rectangular | mummy |
| Packed weight (lb) | 2.44 | 1.81 |
| Packed size | 8 x 13 in | 7 x 13 in |
| Zipper side | right | left or right |
| Product note | 550-fill DriDown; ISO comfort 31F, lower limit 21F; regular weight 2 lb 7 oz | 850+ FP ethically-sourced premium goose down; USA made; full-length #5 YKK zipper; 6'0" version weighs 1 lb 13 oz |

## Key differences

- Fill power: Cosmic Down 20 Sleeping Bag 550 vs UltraLite Sleeping Bag 850
- Shape: Cosmic Down 20 Sleeping Bag semi-rectangular vs UltraLite Sleeping Bag mummy
- Packed weight (lb): Cosmic Down 20 Sleeping Bag 2.44 vs UltraLite Sleeping Bag 1.81
- Packed size: Cosmic Down 20 Sleeping Bag 8 x 13 in vs UltraLite Sleeping Bag 7 x 13 in
- Zipper side: Cosmic Down 20 Sleeping Bag right vs UltraLite Sleeping Bag left or right
- Product note: Cosmic Down 20 Sleeping Bag 550-fill DriDown; ISO comfort 31F, lower limit 21F; regular weight 2 lb 7 oz vs UltraLite Sleeping Bag 850+ FP ethically-sourced premium goose down; USA made; full-length #5 YKK zipper; 6'0" version weighs 1 lb 13 oz

## What reviewers say

**Cosmic Down 20 Sleeping Bag** — Two whitelisted hands-on testers (CleverHiker, Switchback Travel) reviewed the Kelty Cosmic Down 20 and both call it a strong-value budget 3-season down bag. Both praise its warmth-to-weight ratio, buttery-soft lining, and low price, and both flag it as heavy and bulky for a backpacking-specific bag while noting the large gap between the women's and unisex versions. CleverHiker's tester observed comfortable warmth to 30F against the 20F spec. All six quotes and the one measured value were verified as literal substrings of the fetched source text. (2 sourced reviews.)

## Sources

- Cosmic Down 20 Sleeping Bag: https://kelty.com/products/cosmic-down-20 (kelty.com, verified 2026-06-20)
- UltraLite Sleeping Bag: https://www.westernmountaineering.com/product/ultralite/ (westernmountaineering.com, verified 2026-06-20)

Canonical: https://frontdeskreview.com/gear/sleeping-bags/kelty-cosmic-down-20-vs-western-mountaineering-ultralite/
Cite: Per The Front Desk Review, Cosmic Down 20 Sleeping Bag ($189.95) vs UltraLite Sleeping Bag ($660) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/sleeping-bags/kelty-cosmic-down-20-vs-western-mountaineering-ultralite/
License: CC BY 4.0.