Key takeaways
- Polartec High Loft is a tall, airy, low-density fleece insulation.
- Its lofted pile traps lots of warm air for high warmth-to-weight.
- It stays breathable and compressible — blending fleece's feel with more warmth.
- It's used as a breathable insulating mid-layer in fleece-style insulated jackets.
Polartec brand fleece insulation.
What Polartec High Loft is
Polartec High Loft is a lofted, low-density fleece insulation from Polartec, designed to trap a lot of warm air for excellent warmth-to-weight while remaining breathable and compressible. Its tall, airy pile lofts up like a lightweight insulation rather than a dense fleece.
How it differs from regular fleece
Standard fleece is relatively dense; High Loft has a much taller, airier, lower-density pile that traps more warm air — so it’s warmer for its weight and more packable than basic fleece, while keeping fleece’s breathability and soft feel. It behaves more like a breathable insulation than a plain fleece.
For a cold but active day, a hiker wears a High Loft jacket as their mid-layer — getting more warmth for the weight than a basic fleece, with the breathability to keep them from overheating on the climbs, where a dense puffy would.
Where it’s used
High Loft is used as a breathable insulating mid-layer, often in fleece-style insulated jackets for active cold-weather use — a good choice for stop-and-go activities where a breathable lofted layer beats a less breathable puffy. It sits alongside other synthetic insulations in the warmth-layer lineup.
The bottom line
Polartec High Loft is lofted fleece insulation — a tall, airy, low-density pile that traps lots of warm air for high warmth-to-weight while staying breathable and compressible. It blends fleece's soft, breathable feel with more warmth per gram, making it a great breathable insulating mid-layer for active, stop-and-go cold-weather use.
Frequently asked questions
What is Polartec High Loft?
Polartec High Loft is a lofted, low-density fleece insulation from Polartec. It uses a tall, airy pile that traps a lot of warm air for its weight, giving it excellent warmth-to-weight while staying breathable and compressible. It bridges the gap between a traditional dense fleece and a lightweight lofted insulation.
How is High Loft different from regular fleece?
Regular fleece is relatively dense; Polartec High Loft has a much taller, airier, lower-density pile that lofts up to trap more warm air, so it's warmer for its weight and more compressible than standard fleece, while keeping fleece's breathability and soft feel. It behaves more like a breathable insulation than a basic fleece.
Where is Polartec High Loft used?
It's used as a breathable insulating mid-layer, often in 'fleece-style' insulated jackets and pullovers where you want warmth, breathability, and compressibility for active cold-weather use. It's a good choice for stop-and-go activities where a breathable, lofted warmth layer beats a wind-blocking but less breathable puffy.
Sources
- Polartec fabric technologies — Polartec
- Insulation & layering — The Mountaineers