The Great Debate: Down vs Synthetic
Choosing between down and synthetic insulation is one of the biggest decisions when buying a sleeping bag. Both have their place, and understanding the trade-offs helps you make the right choice.
| Feature |
Down |
Synthetic |
| Warmth-to-Weight |
Excellent |
Good |
| Compressibility |
Excellent |
Fair to Good |
| Wet Performance |
Poor (unless treated) |
Excellent |
| Dry Time |
Slow |
Fast |
| Durability/Lifespan |
10-20+ years |
3-8 years |
| Price |
Higher |
Lower |
| Maintenance |
More care required |
Easy care |
| Allergies |
Possible concern |
Hypoallergenic |
Down Insulation: Deep Dive
Down is the fluffy undercoating found beneath the feathers of geese and ducks. It's nature's best insulator, trapping tiny pockets of air that retain body heat.
How Down Works
Each down cluster has thousands of tiny filaments that create air pockets. These pockets trap warm air and prevent heat loss. The quality of down is measured by "fill power" - how much space one ounce of down occupies.
Fill Power Ratings
- 550-600 Fill: Entry-level down, more affordable but heavier for equivalent warmth
- 650-700 Fill: Good quality down, solid balance of performance and price
- 750-800 Fill: High-quality down, excellent warmth-to-weight ratio
- 850-950 Fill: Premium down, best for ultralight applications
Down Advantages
- Unmatched warmth-to-weight ratio
- Compresses to very small sizes
- Incredibly long lifespan (decades)
- Breathes well, reducing clamminess
- Natural, sustainable material
- Maintains loft year after year
Down Disadvantages
- Loses insulation when wet
- Takes long time to dry
- Higher price point
- Requires careful cleaning
- Not vegan-friendly
- Potential allergen for some
Hydrophobic Down
Modern down treatments (like DriDown, DownTek, and Nikwax Hydrophobic Down) coat down fibers to resist moisture. These treatments:
- Help down maintain loft when damp
- Reduce dry time significantly
- Add minimal cost to the sleeping bag
- Don't last forever (reapply every few years)
Pro Tip: If you're choosing down, always look for hydrophobic-treated down. It addresses down's biggest weakness with minimal trade-offs.
Synthetic Insulation: Deep Dive
Synthetic insulation uses polyester fibers engineered to mimic down's structure and performance. Modern synthetics have improved dramatically.
Types of Synthetic Insulation
- Short-Staple: Cut fibers that mimic down's feel, soft but less durable
- Continuous Filament: Long strands that maintain loft better over time
- Hollow Core: Fibers with hollow centers for better warmth
- Microfiber: Very fine fibers for improved compressibility
Synthetic Advantages
- Insulates even when wet
- Dries very quickly
- More affordable
- Easy to clean and maintain
- Hypoallergenic
- No ethical concerns
- Works well in humid climates
Synthetic Disadvantages
- Heavier for same warmth
- Bulkier packed size
- Loses loft over time
- Shorter lifespan
- Less breathable
- Petroleum-based materials
Which Should You Choose?
Choose Down If:
- Weight and packed size are priorities (backpacking, ultralight)
- You camp primarily in dry conditions
- You want a bag that lasts 15-20+ years
- You're willing to invest more upfront
- You need maximum warmth in minimal space
Choose Synthetic If:
- You camp in humid or wet environments
- Budget is a primary concern
- You want easy-care, low-maintenance gear
- You have down allergies
- Weight isn't critical (car camping)
- You're a beginner building your first kit
The Middle Ground: Some bags use hybrid designs with down on top (where it stays dry) and synthetic on bottom (where moisture from sleeping pads can accumulate). These offer a good compromise.
Real-World Recommendations
Best Down Sleeping Bags
Best Synthetic Sleeping Bags