The down versus synthetic debate has raged among outdoor enthusiasts for decades. Both insulation types have passionate advocates, and the reality is that each excels in different situations. Rather than declaring a winner, this guide explores the strengths and weaknesses of each approach, helping you choose the right insulation for your specific needs and conditions.
Understanding how insulation works at a fundamental level makes the comparison clearer. All insulation works by trapping air—it's the trapped air that provides warmth, not the material itself. Different insulation types simply achieve this air-trapping goal through different means, with varying trade-offs in weight, packability, wet performance, and environmental impact.
Understanding Down Insulation
Down refers to the fluffy clusters found beneath the outer feathers of ducks and geese. These clusters have an incredibly high warmth-to-weight ratio, making down the gold standard for lightweight, packable warmth.
Fill Power Explained
Fill power measures down quality by indicating how many cubic inches one ounce of down occupies when fully lofted. Higher fill power means the down traps more air per gram, providing more warmth for less weight. Common ratings range from 550 to 900+ fill power.
- 550-600 fill: Budget-friendly, heavier, adequate warmth
- 650-700 fill: Good balance of performance and value
- 750-800 fill: Excellent warmth-to-weight ratio, higher price
- 850+ fill: Premium performance, maximum warmth for minimum weight
Fill power alone doesn't tell the whole story—fill weight (how much down is in the jacket) matters equally. A jacket with 100 grams of 650-fill down provides comparable warmth to one with 80 grams of 800-fill down.
Down's Advantages
Nothing matches down for warmth-to-weight efficiency. An 800-fill down jacket weighing 300 grams can provide equivalent warmth to a synthetic jacket weighing 450 grams or more. Down also compresses smaller than synthetic insulation, making it easier to pack for travel or carry as an emergency layer.
Quality down maintains its loft through hundreds of compression-expansion cycles, often lasting a decade or more with proper care. Well-maintained down jackets frequently outlast their synthetic equivalents.
Down's Weaknesses
Wet down is nearly useless. When down gets saturated, the clusters collapse and lose their ability to trap air. Drying takes a long time, and until fully dry, you're carrying extra weight with minimal insulation benefit. This makes traditional down a poor choice for consistently wet environments.
Down also costs more than equivalent synthetic insulation and requires more careful maintenance to preserve performance over time.
Modern "hydrophobic" or "water-resistant" down treatments address wet performance somewhat. Treated down retains more loft when damp and dries faster, though it still doesn't match synthetic in sustained wet conditions. Look for treatments like DownTek or Nikwax Hydrophobic Down.
Understanding Synthetic Insulation
Synthetic insulation uses polyester fibres arranged to mimic down's air-trapping properties. While unable to match down's warmth-to-weight ratio, synthetic offers distinct advantages that make it preferable in many situations.
Types of Synthetic Insulation
Synthetic insulations fall into two main categories: short-staple fibres and continuous filament. Short-staple options like PrimaLoft Gold or Thermore offer the closest approximation to down's feel and compressibility. Continuous filament options like Climashield APEX provide excellent wet performance and durability but compress less efficiently.
Brand-name synthetic insulations are generally worth seeking out—quality varies significantly, and no-name synthetics often disappoint in warmth, durability, or both.
Synthetic's Advantages
Wet performance is synthetic's killer feature. Synthetic fibres don't absorb water, so they maintain most of their loft and insulating properties even when soaked. They also dry remarkably fast—often hours rather than the day-plus required for down. For wet climates like much of coastal Australia, this advantage is substantial.
Synthetic is also generally more affordable than equivalent-warmth down, and maintenance is more forgiving. Machine washing without special detergents or drying protocols is typically fine.
Synthetic's Weaknesses
Weight and packability are synthetic's main limitations. Matching down's warmth requires more material, meaning heavier jackets that pack larger. For ultralight backpacking or travel where every gram counts, down typically makes more sense.
Synthetic insulation also has a shorter lifespan than down. The fibres gradually break down with repeated compression, losing loft over time. Most synthetic jackets perform well for three to five years of regular use before noticeable degradation occurs.
Choose down for dry, cold conditions where weight and packability matter. Choose synthetic for wet climates, high-moisture activities, or when budget is a primary concern. Many outdoor enthusiasts own both types for different situations.
Ethical Considerations
Down sourcing has legitimate ethical concerns that informed consumers should understand.
Live Plucking and Force Feeding
Down is a byproduct of the poultry industry, but practices vary widely. Live plucking—removing feathers from living birds—causes suffering but maximises harvest. Force-feeding for foie gras production is another concern in geese raised for both meat and down.
Responsible Down Standards
Certification schemes address these concerns. The Responsible Down Standard (RDS) prohibits live plucking and force feeding, requiring traceability throughout the supply chain. The Global Traceable Down Standard and similar certifications offer comparable assurances. Major outdoor brands increasingly use only certified down.
If ethics matter to you, look for certified down or choose synthetic alternatives. Quality synthetic insulation avoids animal welfare concerns entirely, though it carries its own environmental footprint through petroleum-derived materials.
Environmental Considerations
Both insulation types have environmental impacts. Down is a byproduct of an existing industry, but industrial poultry production has significant environmental effects. Synthetic insulation derives from petroleum and sheds microplastics during washing, contributing to plastic pollution.
Recycled synthetic insulations (like PrimaLoft Black Insulation Eco) address some environmental concerns by using recycled plastic bottles. The most sustainable choice may be buying quality pieces that last many years, reducing overall consumption regardless of insulation type.
Choosing Based on Activity
Different activities favour different insulation choices.
Urban Wear and Commuting
For general urban use in Australian cities, either insulation works well. Down offers a slimmer profile under outer layers and packs small for carrying, while synthetic handles unexpected rain better. Personal preference and budget often determine the best choice for this use case.
Hiking and Backpacking
In dry alpine conditions, down's weight savings make a compelling case. For coastal walks, multi-day trips where rain is likely, or high-exertion activities generating significant moisture, synthetic's wet performance proves its worth. Many experienced hikers carry a waterproof stuff sack to protect down, enabling its use in variable conditions.
Climbing and Mountaineering
High-altitude and serious cold typically favour down for its unmatched warmth-to-weight ratio. At these temperatures, snow is less likely to melt on the jacket, reducing wet concerns. Many expedition-weight garments use down because the weight penalty of synthetic at extreme warmth levels becomes prohibitive.
Everyday Active Use
For regular gym commutes, running errands, or activities where the jacket may get sweaty, synthetic is often more practical. It handles moisture from both rain and perspiration better, and less careful maintenance suits busy lifestyles.
Some jackets use both insulation types strategically—down in low-moisture areas like the front and back panels, synthetic in high-moisture zones like underarms and hoods. These hybrids attempt to capture the best of both worlds for active use.
Making Your Decision
Consider these questions when choosing between down and synthetic:
- Climate: Is your area frequently wet, or primarily dry and cold?
- Activity level: Will you generate significant body moisture through exertion?
- Weight priority: Is minimising weight critical for your intended use?
- Budget: Are you willing to pay the premium for quality down?
- Ethics: Do animal welfare concerns influence your purchasing decisions?
- Maintenance: Are you prepared for down's more demanding care requirements?
There's no universally correct answer. Both down and synthetic insulation serve millions of users well every day. Understanding their trade-offs enables you to match your choice to your specific circumstances rather than following marketing claims or outdated advice.
For many Australians, owning both types makes sense—a quality down jacket for cold, dry days and travel, and a synthetic option for wet weather and high-output activities. This approach provides maximum versatility without requiring a single jacket to do everything.