Down is the warmest of the three for its weight, but only while it stays dry. REI’s layering guide calls down the warmest for its weight and adds that it loses insulation when wet, while fleece stays warm when damp and dries quickly, and wool resists odour and does not chill you when it holds a little moisture.
So the real answer depends on weather, activity and budget. Below is a side-by-side table built from REI’s guides, a note on where Advnture’s fleece and wool comparison lands, and a decision list for common situations. For the full fabric tour, read winter fabrics explained, and for the wardrobe context start with the winter clothes for women guide.
The Head-to-Head Table
| Factor | Wool (merino) | Fleece | Down | Source |
|---|---|---|---|---|
| Warmth for weight | Good | Good | Best | REI (down); others ours |
| When wet | Does not chill you with moisture in its core; dries slowly | Stays warm when damp; dries quickly | Clumps and loses loft; slow to dry | REI |
| Wind | Not covered in sources we read | Wind passes through | Depends on the outer shell | REI (fleece) |
| Odour | Resists odour-causing bacteria | Not covered in sources we read | Not covered | REI (wool) |
| Durability | Moderate (merino base layer) | Not covered | Needs careful care | REI |
| Price | Varies; not verified | Varies; not verified | Higher fill power costs more | REI jacket guide |
| Care | Follow label; dries slowly | Not covered in sources we read | Detergent-free cleaner, low-heat drying with tennis balls, hang to store | REI |
Where the table says ‘ours’ or ‘not covered’, we did not find the claim in the sources we read, so treat those cells as general guidance only. We have not tested garments ourselves.
Which Is Warmest for Everyday Winter Days?
For dry, cold days, down. REI says fill power ranges from about 450 to 900, and higher numbers trap more air. For a normal commute, a 650-fill jacket can be much cheaper than loftier ones. For wet or changeable days, synthetic insulation or fleece may keep you warmer in practice, since both keep working when damp. If your coat is the main concern, compare options in the best winter jackets for women guide.
Is Wool or Fleece Better?
Advnture’s 13 January 2024 comparison of the two says there is no clear winner, and that matches REI’s notes. Fleece wins on drying speed and damp warmth. Wool wins on odour resistance and feel. Fleece also arrived late: Advnture says it was introduced as Polartec in 1979. If you wear one layer for several days, choose wool. If you sweat and need quick drying, choose fleece.
Which Should You Choose in Each Situation?
| Situation | Our pick | Why |
|---|---|---|
| Dry, very cold commute | Down jacket over a wool knit | Warmest for weight |
| Rainy winter city | Synthetic jacket over fleece | Both keep working when damp |
| Office all day | Merino base and wool knit | Resists odour; neat look |
| Walk or light exercise | Synthetic base, fleece, shell | Fast drying and wind protection |
| Long trip with limited luggage | Packable down or synthetic jacket, merino base | Packs small and layers well |
| Tight budget | Synthetic fill and fleece | REI says synthetic is generally cheaper |
The picks are our recommendations. Climate, body temperature and activity change the best answer, so use them as a starting point. For examples of how to combine these pieces without bulk, read how to layer winter clothes without looking bulky.
Can You Combine Them?
Yes, and that is usually best. REI’s three-layer system pairs a moisture-wicking base with an insulating middle and a protective outer. A merino base, a fleece middle and a down or wool outer combine the strengths and cover the weaknesses. Use our winter wardrobe checklist to see which jobs you already cover.
What About Price?
REI says synthetic insulation is generally less expensive than down, and gives a 650-fill down jacket as costing about half as much as loftier options. We did not verify fleece and wool prices across brands. If you want a discount, compare prices over time. Our price history tracker guide explains how.
What Should You Look for on Labels?
Check the main fabric percentage, the fill type for jackets and the fill power for down. REI says fill power is the cubic inches filled by one ounce of down, and that duck down generally tops out at 750 or 800. Premium goose down can reach 900 or higher.
Look for care instructions you can follow at home. A jacket that needs special cleaning may cost more over time. For help with the style side of the decision, read winter fashion trends for women and the winter coats buying guide.
