Generally cheaper, hypoallergenic, and continues to insulate even when damp. The downside is that it is bulkier and heavier than down and its warmth can diminish over time as fibers break down. 3. Finding the Right Shape

A survival-only rating indicating the temperature at which a standard woman can survive for six hours without hypothermia; it is not a comfort guide.

The fill material determines the bag's weight, compressibility, and performance in wet weather.

Buying a sleeping bag requires balancing warmth, weight, and price. To choose the right one, focus on its temperature rating, the type of insulation, and its shape relative to how you plan to use it—whether for car camping or backpacking. 1. Decoding Temperature Ratings

The temperature at which a "standard woman" (or cold sleeper) can sleep comfortably in a relaxed position.

Shape affects how much heat the bag retains and how much room you have to move.

Offers the best warmth-to-weight ratio and is highly compressible, making it ideal for backpacking. However, it is more expensive and loses its insulating properties if it gets wet, though "hydrophobic down" treatments can mitigate this.

Tapered for a body-hugging fit to maximize warmth and minimize weight. Best for backpacking.