You are standing in a fabric showroom, two swatches in hand. One is fluffy, lofty, and traps air visibly between its fibers. The other feels denser, smoother, with a soft looped back. Both are knitted fabrics. Both claim to be winter-ready. But which one actually keeps the cold out better?
The answer is not as simple as picking the thicker one. Polar fleece and French terry serve different roles in a winter jacket, and their warmth depends on construction, weight, and intended use. Polar fleece is engineered for insulation — it traps heat in a layer of air pockets. French terry, originally a sweatshirt fabric, offers moderate warmth with better drape and moisture management.
This article compares the two fabrics across thermal performance, weight, breathability, durability, and cost. We draw on industry standards and real production data from a knitted fabric manufacturer with over 30 years of experience. By the end, you will know exactly which fabric fits your jacket design — and why.
Polar fleece provides 1.5 to 2 times more thermal insulation than French terry at the same fabric weight due to its brushed, air-trapping structure.
French terry is 20–30% more breathable than polar fleece, making it better for active wear or mild winter conditions.
Polar fleece typically weighs 180–350 g/m²; French terry ranges from 200–400 g/m² — weight alone does not determine warmth.
French terry resists pilling better than polar fleece in high-friction areas like elbows and cuffs.
For extreme cold, choose polar fleece as a mid-layer; for casual, everyday jackets, French terry offers a better balance of warmth and comfort.
Warmth in knitted fabrics comes down to one principle: trapped air. Still air is a poor conductor of heat. The more dead air a fabric holds within its structure, the warmer it feels. This is measured as thermal resistance, or clo value. A typical polar fleece jacket has a clo value of 0.5–0.8, while a French terry sweatshirt sits around 0.3–0.5.
But warmth is not the only factor. You also need to consider:
Weight and bulk: Heavier fabrics trap more air but add weight to the jacket.
Breathability: A fabric that traps too much moisture can feel cold when sweat evaporates.
Durability: Abrasion resistance affects how long the fabric maintains its insulating properties.
Moisture management: Wicking ability keeps the wearer dry and comfortable.
The table below summarizes these factors for both fabrics.
| Factor | Polar Fleece | French Terry |
|---|---|---|
| Thermal insulation (clo value) | 0.5–0.8 | 0.3–0.5 |
| Typical weight range | 180–350 g/m² | 200–400 g/m² |
| Breathability (ASTM D737) | 50–150 cfm | 100–250 cfm |
| Pilling resistance (ASTM D4970) | Grade 3–4 | Grade 4–5 |
| Moisture wicking | Good (hydrophilic treatment often added) | Moderate (natural cotton wicking) |
| Best use case | Mid-layer insulation, cold-weather outerwear | Casual jackets, hoodies, activewear |
| Cost per yard (typical) | $6–$12 | $5–$9 |
Polar fleece is a synthetic knitted fabric, typically made from 100% polyester or a polyester blend. Its defining feature is a brushed surface on one or both sides. The brushing process lifts fibers, creating a dense layer of tiny loops that trap air. This structure gives polar fleece its characteristic soft, fluffy feel and high thermal efficiency.
Thermal performance: A 250 g/m² polar fleece can provide warmth comparable to a 400 g/m² French terry. The reason is the air-to-fiber ratio. In polar fleece, up to 80% of the fabric volume is air. In French terry, that figure drops to 60–65%. Industry testing per ASTM F1868 shows polar fleece retains 35–50% more heat than French terry at equal thickness. Breathability trade-off: The same dense fiber structure that traps heat also restricts airflow. Polar fleece has a typical air permeability of 50–150 cubic feet per minute (cfm) under ASTM D737. This is fine for low-activity use but can cause overheating during high exertion. Many manufacturers apply hydrophilic finishes to improve moisture transport. Durability concerns: The brushed surface is prone to pilling, especially in high-friction areas. ASTM D4970 pilling tests typically rate polar fleece at Grade 3–4 (moderate pilling after 5,000 cycles). This is acceptable for mid-layers but less ideal for outer shells that rub against backpack straps or seat belts. Production insight: As a knitted fabric manufacturer, Tianruide produces polar fleece in weights from 180 g/m² (lightweight) to 350 g/m² (heavyweight). The integrated weaving-to-dyeing process ensures consistent fiber density and color fastness across bulk orders. For winter jackets, a 280–320 g/m² polar fleece offers the best balance of warmth and drape.
French terry is a knit fabric with smooth face and looped back. The loops are not cut or brushed — they remain intact, creating a textured surface that traps some air but allows more airflow than fleece. French terry is commonly made from cotton, cotton-polyester blends, or 100% polyester.
Thermal performance: French terry provides moderate insulation. A 300 g/m² French terry jacket has a clo value of about 0.4, suitable for temperatures between 10°C and 15°C (50°F–59°F). Below that, it needs a windproof outer layer or additional insulation. Breathability advantage: The open loop structure gives French terry an air permeability of 100–250 cfm — roughly double that of polar fleece. This makes it ideal for active wear or mild winter conditions where moisture management matters more than extreme warmth. Durability advantage: Because the loops are not brushed, French terry resists pilling better. ASTM D4970 tests typically rate it at Grade 4–5 (slight to no pilling). This makes it a better choice for jacket elbows, cuffs, and areas that see frequent abrasion. Moisture management: Cotton French terry absorbs moisture rather than wicking it away. Polyester blends improve wicking but reduce breathability. For winter jackets, a 65/35 polyester-cotton blend offers a good compromise. Application note: French terry is widely used in casual jackets, hoodies, and sportswear. It also appears in unexpected places — for example, Pocket fabric is a core auxiliary material for clothing, als o used in waistband linings where moderate warmth and low bulk are required.
Choose polar fleece when your primary goal is warmth per unit weight. This fabric excels as a mid-layer under a shell jacket in cold climates. It is also the better choice for:
Winter camping and hiking: Lightweight insulation that packs small.
Urban winter coats: A 300 g/m² fleece lining can replace a thicker synthetic insulation layer.
Children's outerwear: Soft, non-irritating, and easy to wash.
Polar fleece is less suitable for high-exertion activities where sweat buildup becomes a problem. It also performs poorly in wind — a 10 mph wind can reduce its effective insulation by 40%. Pair it with a windproof outer layer for best results.
Choose French terry when you need a fabric that balances warmth with comfort and durability. This fabric works well for:
Casual winter jackets: A lined French terry jacket with a windproof membrane is comfortable for daily commutes.
Athleisure and activewear: Breathable enough for light exercise, warm enough for cool weather.
Layering under a shell: French terry's smooth face slides easily under a jacket without bunching.
French terry is also the better choice for garments that see heavy use. Its superior pilling resistance means it looks newer longer. For applications like automotive interiors, where fabric must withstand constant friction, French terry's durability is a clear advantage. In fact, Warp-knitted car roof fabric often uses a French terry structure for its combination of softness and abrasion resistance.
A common misconception is that heavier fabric equals warmer fabric. This is not true. A 400 g/m² French terry may feel substantial, but its thermal resistance is lower than a 280 g/m² polar fleece. The reason is fiber density versus air volume.
Consider two fabrics:
Fabric A: 280 g/m² polar fleece, 80% air volume, clo value 0.6
Fabric B: 400 g/m² French terry, 60% air volume, clo value 0.45
Fabric A is 30% lighter but 33% warmer. The extra weight in Fabric B comes from denser fiber packing, not more trapped air. For winter jackets, prioritize air-trapping structure over sheer weight.
Warmth is not just about the fabric itself — it is about how the fabric performs in real conditions. Two factors dramatically affect perceived warmth:
Moisture: Wet fabric loses 80–90% of its insulating ability. Polar fleece, being hydrophobic polyester, dries quickly and retains some insulation when damp. Cotton French terry absorbs water and becomes cold and heavy. For wet climates, choose polyester French terry or polar fleece. Wind: A 5 mph breeze can cut the effective clo value of polar fleece by half. French terry, with its tighter surface, fares slightly better but still loses insulation in wind. Both fabrics benefit from a windproof outer layer.
When sourcing fabric for winter jackets, look for these standards:
ASTM F1868: Standard test method for thermal resistance (clo value) of clothing materials.
ASTM D737: Air permeability test — lower values mean less breathability.
ASTM D4970: Pilling resistance test — Grade 4 or higher is preferred for outerwear.
ISO 11092: Measurement of thermal and water-vapor resistance under steady-state conditions.
A reputable knitted fabric manufacturer will provide test data for these standards on request. Tianruide, for example, offers full test reports for all fleece and French terry fabrics, including weight, thickness, air permeability, and pilling grade.
Polar fleece is warmer. At the same weight, polar fleece provides 35–50% more thermal insulation than French terry due to its brushed, air-trapping structure.
Yes, but only for mild winter conditions (10°C–15°C / 50°F–59°F). For colder temperatures, use French terry as a lining or combine it with a windproof outer layer.
French terry lasts longer in high-friction areas. Its unbrushed loop structure resists pilling better than polar fleece. ASTM D4970 tests show French terry at Grade 4–5 versus polar fleece at Grade 3–4.
Moderately. Polar fleece has an air permeability of 50–150 cfm, which is lower than French terry (100–250 cfm). It can trap heat and moisture during high exertion.
For polar fleece, 280–320 g/m² is ideal for a mid-layer or lightweight outer jacket. For French terry, 300–400 g/m² provides moderate warmth with better breathability.
Yes. Polar fleece is common in camping and hiking jackets. French terry is used in casual outdoor wear and even in specialized applications like Tent outdoor gear where a soft, durable interior lining is needed.
Polar fleece and French terry are not competitors — they are complementary fabrics for different winter jacket scenarios.
For maximum warmth in cold, dry conditions: Polar fleece wins. Its air-trapping structure provides superior insulation per gram.
For everyday comfort, durability, and breathability: French terry wins. It handles moisture better, resists pilling, and feels more comfortable against the skin.
If you are designing a winter jacket for a customer who will wear it in sub-zero temperatures, spec polar fleece. If the jacket is for casual wear in mild winters, French terry is the smarter choice.
Both fabrics are available from Tianruide, a knitted fabric manufacturer with over 30 years of experience in fleece and French terry production. The integrated weaving-to-dyeing process ensures consistent quality across bulk orders, and expert guidance is available for custom fabric solutions.
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