Best Lightweight Down Jacket & Pants for Backpacking 2023 – GWC Mag

Understanding total warmth, and warmth-to-weight using down volume

When comparing down jackets, warmth-to-weight and total weight are the best indicators of performance. An insulative jacket’s primary job is to (1) keep you warm, and (2), not weigh down your pack. Thus the warmth-to-weight ratio is king.

To understand a jacket’s total warmth and warmth-to-weight ratio, you should begin by knowing its total volume of uncompressed down. This can be found by multiplying the fill weight (measured in oz) times the fill power (measured in cubic inches). Our top pick, the Zpacks Goose Down Jacket has 3230 cubic inches of uncompressed down stuffed into its baffles.

Another jacket, the Mountain Hardwear Ghost Whisperer, has only 2400 cubic inches of down crammed inside its baffles. So we know that the Zpacks jacket has about 33% more down and thus is approximately 33% warmer.

We can take that a step further to calculate an approximation of warmth-to-weight by dividing total cubic inches of uncompressed down by the total weight of the garment.

This statistic correlates very closely with warmth-to-weight, but does not give an actual warmth-to-weight since we are not measuring thermal barrier efficiency nor how insulative properties of the fabric factors in. But roughly speaking, the higher the uncompressed down volume per ounce of garment weight, the better the warmth-to-weight ratio should be in theory.

Comparing Zpacks to Ghost Whisperer again, we see that Zpacks has 475 cubic inches of down per ounce of jacket weight, where as Ghost Whisperer only has 274 cubic inches per ounce of jacket weight. Thus we can infer that the Zpacks jacket delivers a whopping 73% higher warmth-to-weight ratio. 

Focus on down insulation over fleece and base layers

For hiking and backpacking in cold weather, down is the most weight-efficient insulator you can carry into the backcountry. As such, we prefer to maximize our use of down and minimize our use of fleece and merino wool (or similar) base layers. A pair of merino tights plus a pair of fleece camp pants could weigh as much as a pound or more, and will be less warm and twice as heavy as a pair of down pants.

For best results in cold weather camping, it’s critical that you have head-to-toe insulated-wear, including a hooded jacket, pants, and booties. Since down does 80% of the insulating, we aren’t very particular about fancy winter base layers or fleece. Even summer-weight base and mid-layers will do the job, so long as you have a good lightweight down jacket and pants.

Lightweight down jacket insulation vs moisture

Experienced backpackers basically never allow their down to get soaked. Over the past ten years, we’ve spent hundreds of nights in the backcountry and toughed out some really gnarly weather. Not once has our down apparel or sleeping bag gotten soaked. It has occasionally gotten damp, but it’s a myth that down does not insulate when lightly or moderately wet, or that it’s constantly getting soaked on every hiking trip.

What’s more, basically every down garment now uses hydrophobic plumes which have been coated in DWR to ensure that they don’t clump up or de-loft in wet conditions. In short, we think manufacturers are trying to instill a fear of moisture to help sell their synthetic insulation layers.

While synthetics do perform slightly better than down when wet, it is better to focus on keeping the entire system dry than worrying about what happens if it does get wet. An ounce of prevention is worth a pound of cure. What’s more, synthetics are definitely no joy to wear when wet either.

Stretchy down jackets and hyper breathable synthetic insulation are overrated

Many brands are now manufacturing insulation layers with stretch and ultra breathable synthetic insulation. While that’s great for mountaineering and specific trips with unusually challenging day-time weather, we feel that those supposed benefits matter very little for the typical backpacker. And in fact they come with a severe cost. Stretchy and super breathable insulation is typically heavier, more expensive, and less warm.

Over the course of an average backpacking season, the typical down jacket will spend about 99% of its time either in your backpack, or worn at camp. Since it’s basically never worn while actually hiking, stretch and breathability are hardly beneficial at all.

What’s more, the nylon fabrics commonly used in down jackets are rather slippery, which means they will move with you, thus mitigating some of the need for stretch. Hyper breathable synthetic insulation layers forfeit some of their warmth-to-weight to allow warm moist air to escape. That’s great when you’re on the go, but like we said, down jackets are mostly not worn on the go in nearly all backpacking scenarios.

Why we prefer hooded lightweight down jackets for backpacking

Given our druthers, we will always choose a lightweight down jacket with a hood over one without. This is because we prefer to camp with ultralight hoodless quilts, rather than traditional sleeping bags, and our down jacket hood adds redundancy to the system when additional head insulation is required.