Anyone who has ever stepped inside a sporting-goods store has heard the debate between down and synthetic insulation. You need only look at the sleeping bag section, and a storeroom attendant will appear within moments to offer you a full dissertation on the topic. However, when it comes to insulated jackets, we’ve found that conventional wisdom just doesn’t apply.
The reason for this disconnect is that the down vs. synthetic debate has been framed exclusively through the prism of sleeping bags.
Sleeping bags are rarely designed to be fully waterproof. Instead, they’re designed to be lightweight and packable, making them more susceptible to getting wet. Insulated ski jackets, on the other hand, are frequently constructed using waterproof fabrics and seam-sealing tape to completely lock out moisture. While there might be legitimate concern of a down sleeping bag getting wet, it’s unlikely the down insulation of a waterproof jacket will get wet unless you rip the fabric.
Insulation for Sleeping Bags
Down: Superior insulation and loft when used in cold, dry conditions, but worthless when wet.
Synthetic: Slightly less insulation and loft, but retains thermal properties even when wet.
Down: Superior insulation, exceptionally lightweight, higher loft results with puffier appearance.
Synthetic: Slightly less insulation, slightly heavier, lower loft results with slimmer, more flattering appearance.
So then, is there really a difference when it comes to jackets? Yes, but it’s more about a matter of style.
High-grade down has a lot more loft than synthetics, making it better at retaining heat but also adding to its overall volume. Few people care how they look when they’re curled up in a sleeping bag, but finding an insulated jacket with a flattering fit can be a real trick. Synthetics, in this case, offer a slimmer, less bulky look in exchange for slightly reduced performance — a trade-off that might be very appealing to the more sartorially minded.
So if you’re seeking stylish warmth (e.g., a winter jacket for the city) but are concerned that your jacket might make you look a little too voluminous, then synthetic insulation might be a good option.