How to Choose a Sleeping Bag

Picking the wrong sleeping bag wastes money and ruins sleep. Most beginners focus on the wrong specs and end up with a bag that's either too heavy, too cold, or both.

Temperature Rating

This is what matters most. Manufacturers test in controlled lab conditions with thermal underwear and an insulating pad underneath. Real-world conditions are harsher. A sleeping bag rated to 20°F will actually keep most people warm to around 35°F.

Look for EN/ISO tested ratings, which provide consistent, comparable numbers across brands. The "comfort" temperature is what you want to use for planning—not the "lower limit" or "extreme" ratings. Those are survival ratings, not sleeping comfort.

To choose your rating: pick the lowest temperature you're likely to encounter on your trips, then add 10-15°F as a safety buffer. A 20°F bag covers most three-season camping. A 10°F bag handles high elevations and shoulder seasons. Summer car camping might only need 40°F.

Insulation Type

Down compresses small, feels lighter, and lasts longer when well-maintained. The downside: it fails when wet. Modern down bags have water-resistant treatments, but they're still more vulnerable than synthetic in damp conditions. Down costs more upfront but provides better value over 10+ years.

Synthetic insulation retains warmth when damp and costs less. It's bulkier, heavier, and degrades faster—typically 5-7 years before loft diminishes noticeably. Synthetic makes sense for car camping or budget-conscious buyers who don't mind the weight penalty.

Hybrid bags use down in the top compartment (where your body heat keeps it dry) and synthetic on the bottom (where condensation pools). They're a practical middle ground for around $200-300.

Fill Power and Loft

If you choose down, check the fill power—the number of cubic inches one ounce of down occupies. 650 fill is decent for budget bags. 750-850 fill is industry standard. 900+ fill is premium and gets expensive fast.

Higher fill power means better insulation in less weight. A 850-fill down bag at 20°F weighs around 2-2.5 lbs. A 650-fill bag doing the same job weighs 2.8-3.2 lbs. That extra weight adds up on backpacking trips.

For synthetic, ignore fill power numbers—they're not standardized. Instead, compare total weight. Bags weighing significantly less than competitors at the same temperature rating have better engineering or insulation quality.

Weight and Packed Size

Car camping? Weight barely matters. Backpacking? Every ounce counts. A summer bag should weigh under 2 lbs. A three-season bag should be under 3 lbs. Four-season bags run 3.5-5 lbs depending on how low they go.

Packed size matters more than weight for storage and packing. A good compression bag compresses down to roughly the size of a loaf of bread. If it takes up half your pack, you're making every other piece of gear smaller just to fit it.

Shape and Design

Mummy bags are tapered around your body, minimizing dead air space you have to heat. They're warmer for their weight but more restrictive. Rectangular bags give full freedom to move and often unzip into a blanket. They're warmer than their rating suggests for summer camping but worse for cold trips.

Check the zipper design. Full-length zippers give flexibility but create a cold draft. Half-zippers save weight and reduce drafts. Offset zippers (one side higher than the other) prevent cold spots where zippers meet.

Look for a draft collar around the opening and a footbox baffle that prevents insulation from shifting. These features stop warm air from escaping and cost almost nothing to manufacture, so their absence is a red flag on budget bags.

What Matters Less Than You Think

Waterproof shells sound great but add weight and restrict breathability. A dry sleeping pad and a rain fly on your tent solve the moisture problem better than a waterproof shell. Skip it unless you're doing wet-climate camping regularly.

Attached pads (bags with integrated sleeping pad sleeves) complicate things. You still need a separate pad for insulation, so the attachment serves no real purpose and adds bulk.

Questions to Ask Yourself

• What's the coldest temperature where I'll camp? Add 10-15°F to that.
• Will I backpack or car camp? (Determines acceptable weight.)
• How often will I camp in wet conditions? (Affects down vs synthetic choice.)
• What's my budget? (Determines insulation quality and fill power.)
• How long will I keep this bag? (Down lasts longer; synthetic is cheaper upfront.)

Price Ranges

Under $100: Synthetic bags that work for summer car camping. Heavy, bulky, and won't last long, but fine for testing whether you actually like camping.

$100-250: Sweet spot for most people. Decent synthetic or budget down bags rated 20°F. Good draft collars and construction. Will last 5-7 years with basic care.

$250-500: Premium down bags with solid fill power (750-850), excellent design, and warranties. Three-season option that lasts 10+ years.

Above $500: Specialized bags for extreme conditions, ultra-lightweight designs, or premium brands. Diminishing returns unless you're doing technical mountaineering or have very specific needs.

Final Check

Before buying, verify the bag has EN/ISO tested temperature ratings, not marketing claims. Read actual user reviews for the temperature rating—people will tell you if a "20°F bag" really sleeps warm to 35°F or if it's optimistic. Check for a lifetime warranty (common with down bags) or at least a 5-year synthetic guarantee.

Buy once, camp happy. A sleeping bag is one of the few pieces of gear that actually gets better with use as the insulation settles.