As the weather gets colder, many people start debating which pants are warmer – jeans or fleece leggings. Both options provide warmth and coverage for your legs during chilly weather. But is one definitively warmer than the other? Let’s take a closer look at the factors that impact warmth for each option.
The Makeup of Jeans
Most jeans are made from denim, which is a sturdy cotton twill textile. The fabric consists of cotton warp and weft yarns which are dyed with indigo. After weaving the fabric, it goes through a process to make it stronger and more durable. This involves washing, stone washing, bleaching or other treatments.
The thickness of denim can vary, but most jeans use a medium weight denim. Lightweight denims are 8-9 oz and midweight are 10-12 oz. Heavy denim can be 13-15 oz or more. Heavier denim provides more warmth because there are more tightly woven fibers.
In addition to the weight of the denim, jeans contain the following attributes that impact warmth:
- Multiple layers – Jeans have an inner and outer layer which traps air for insulation.
- Tight fit – Skinny and slim cut jeans hug the body and limit air flow.
- Full length – Having denim cover the entire leg retains more heat.
Modern jeans also often contain some spandex or elastane, around 1-2%. This provides stretch and flexibility in the fabric. But spandex does not have the same insulating properties as cotton.
The Makeup of Fleece-Lined Leggings
Fleece leggings have a different construction from jeans that impacts their warmth. Here are the key elements:
- Fleece lining – Soft and fuzzy fleece on the inside traps air and provides insulation.
- Stretchy fabric – Leggings contain spandex for stretch, allowing for a tight fit.
- Form-fitting – The snugness of leggings limits air flow and retains heat.
- Ankle length – Less coverage than jeans may lead to more heat loss.
Fleece leggings are made from a blend of fabrics. The outer layer is typically made of polyester or nylon. Spandex is added for stretch. The inside consists of thick pile fleece, usually 100% polyester made to mimic wool fleece.
The fleece lining varies in thickness and fluffiness. Thicker, high pile fleece will be warmer. Some leggings have sherpa fleece inside which is extremely soft and warm.
Assessing Warmth and Breathability
To compare the warmth of jeans and fleeced leggings, we need to look at breathability and insulation.
Breathability
- Jeans are moderately breathable due to the cotton material.
- Fleece leggings have less breathability because the synthetic fabrics don’t allow much airflow.
Less breathable fabrics tend to retain more body heat. So fleece leggings have an advantage here.
Insulation
- Jeans provide moderate insulation from their thickness and layered structure.
- Fleece leggings have high insulation because the pile fleece lining traps air.
The thick fleece lining makes fleece leggings better insulators than jeans. The fleece material itself is also warmer than denim.
Temperature Ratings
Outdoor and sporting goods brands have done extensive research on fabric technologies and temperature ratings. According to their assessments:
- Jeans are rated to keep you warm in temperatures 45-55° F (7-13° C).
- Fleece leggings are effective in temperatures 25-35° F (-4 to 2° C).
These numbers indicate fleece leggings outperform jeans by around 10-20° F. So fleece leggings will keep you noticeably warmer.
Situational Factors
While fleece leggings provide more warmth overall, there are some situational factors to consider:
Loose vs Compression Fit
- Loose-fitting jeans have more air flow than skinny jeans.
- Compression leggings don’t allow much airflow and trap heat better.
Tighter fits retain more warmth. So skinny jeans and leggings have an advantage over looser styles.
Layering
- Jeans can be worn over long underwear for extra insulation.
- Leggings fit smoothly under pants, but multiple tight layers can feel restrictive.
Jeans accommodate layering more comfortably than tight leggings.
Wind Protection
- Denim provides protection against wind chill.
- Thin leggings allow cold air penetration.
Jeans hold up better than fleece leggings when facing strong winds.
Wet Conditions
- Jeans take longer to absorb water and dry slowly.
- Fleece soaks up moisture readily and dries quickly.
Wet jeans lose their insulating powers. Fleece leggings retain warmth better when damp.
Covering Up Bare Skin
Along with the pants themselves, coverage for the lower legs impacts warmth. Here are some considerations:
- Jeans cover the ankles and often bunch around the top of boots.
- Leggings end at the ankles allowing cold air to impact skin.
- Tall boots worn over leggings eliminate exposed skin.
Make sure to protect ankles and limit skin exposure when wearing leggings in cold weather.
Conclusion
When choosing between jeans and fleece leggings for warmth, fleece leggings win hands down. Their fleece lining provides superior insulation to trap body heat. Leggings are rated to keep you warm in colder temperatures than jeans.
But jeans have some benefits in windy conditions and for layering. The right pair of jeans can serve as a good cold weather pant. But fleece-lined leggings are guaranteed to keep your legs toasty thanks to their fuzzy fleece interior.
So next time you are deciding what to wear on a cold winter day, choose fleece leggings over jeans for optimal warmth. Add knee-high boots and a thick sweater to complete a cozy winter outfit.
