Best Base Layers for Running in 2023

1. Smartwool Merino 250 Crew

This baselayer will keep you comfortably toasty when running in cold weather. It’s made from 100% Merino wool with flatlock seam construction to prevent chafing.

Interlock knitting allows for a form fit. You can wear the Merino 250 Crew as a single layer when running in mild temps, or use it as an underlayer when you need to beat winter’s harshest chills.

Instead of shoulder seams, the shirt uses shoulder panels. When you wear a backpack, there are no seams to press into your shoulders.

Keeping the garment clean is easy. Simply machine wash on warm on the gentle cycle and then tumble dry on low.

2. Under Armour ColdGear Armour Compression Mock

The Compression Mock from Under Armour has a tight, compression fit that provides a solid base of warmth and dryness. It’s made from a blend of 87% polyester and 13% elastane. Plus, flatlock seam construction prevents stitching from rubbing against your skin.

The base layer has 4-way stretch so you have freedom of movement while you run. Anti-odor materials will help prevent this shirt from smelling like yesterday’s dirty laundry.

While not a true compression shirt, it’s snug fit works well as a tight-fitting base layer to help keep you warm.

3. New Balance Q Speed 1Ntro Long Sleeve

This long-sleeved base layer shirt combines comfort, warmth, and safety.

Unique New Balance HEAT technology pulls moisture away from your skin to keep you dry. Plus, rayon/polyester blend allows for consistent and comfortable airflow.

Reflective details make this shirt safer in low-light if it’s warm enough to wear on its own. We really like the thumbholes on the women’s shirt. Unfortunately, you can only find these on the women’s shirt, not the men’s.

4. Rockay Seamless Long Sleeve

Everything made by Rockay – including this long shirt baselayer – is made with recycled materials. So it’s good for the planet as well as for your runs!

Rockay’s long sleeve uses recycled plastic for 81% percent of the shirt in the nylon material. The other 19% is polyester for comfort and increased sweat wicking. This also helps the shirt stretch to keep you comfortable while running.

The seamless design is great for preventing chafing and hot spots. And this shirt has technology built-in to resist odor.

5. Icebreaker Merino 175 Everyday Long Sleeve 1/2 Zip

You don’t have to choose between substance and style with the Icebreaker 175 Everyday 1/2 Zip. This long-sleeved running shirt keeps you dry and warm. Merino wool is soft and isn’t scratchy – and unlike polyester shirts – stays odor-free.

This shirt is tough yet won’t weigh you down. It is water-resistant and breathable. You’ll be insulated from rain and snow, but heat and sweat are still pulled away from your body. The thinner merino wool layer keeps you warm without overheating.

The shirt has a short zipper at the top which drops down to about mid-chest. Zip it up to protect your neck from the winter chill or leave it unzipped to reduce any build-up of body heat.

6. Craft Fuseknit Comfort Long Sleeve

This lightweight, long-sleeved shirt is soft and stretchy. Body-mapped fabric structures allow for efficient thermal regulation. You’ll stay comfortably warm–not hot and sweaty.

The unique Fuseknit technology uses seamless knit to prevent chafing and irritation, especially when wearing other clothing on top. It’s made from 67% polyester, 31% polyamide and 2% elastane. The semi-relaxed fit conforms to your body shape while remaining loose enough to allow productive airflow.

The garment is also quick to dry. Moisture is wicked away, instead of allowed to saturate the material. You can run in pouring rain without the shirt becoming soaked and freezing. It’s suitable for mild, cool and cold temperatures.

7. Nike Pro Warm Long Sleeve

Looking for a base layer that fits as comfortably as your favorite T-shirt? Try this Nike long-sleeve. It’s made from a soft DriFIT fabric consisting of 88% polyester and 12% spandex.

The top is lightweight and breathable. Sweat and moisture are pulled away from your skin. Additionally, a flat-seam design helps prevent abrasions and irritations against your skin.

The semi-fit style is great if comfort is your main consideration. However, the shirt still fits snugly enough that you can easily layer other garments on top.

This top is also made with 75% recycled fabric, so it’s environmentally friendly – and will keep you warm.

The women’s version costs a bit more but is made with thicker, warmer material. It also features a built-in mitten with thumbholes plus a large, zippered side pocket.

8. Under Armour ColdGear Base 4.0 ½ Zip

It’s like wearing a flexible suit of armor that protects you from the cold! The 4.0 Crew base layer from Under Armour has a brushed negative grid interior that traps hot air, keeping you warm even in the coldest conditions. It’s made from 92% polyester and 8% elastane.

The next-to-skin fit hugs your body tightly but remains comfortable. Four-way stretch construction allows you to move in any direction without hindrance.

It’s fast-drying even in wet conditions. Under Armour’s microthread material wicks away sweat and body heat while a mesh panel in the back of the shirt provides increased ventilation.

9. Salomon Essential Seamless Midlayer

This breathable base layer has the features you want when running. And it works easily as well for a base layer on cold days or an outer layer during cool and mild weather.

Active Fit construction allows for a complete range of movement with no chafing or mobility restrictions.

Plus, the fabric prevents moisture from soaking through the material and dries quickly. Seamless stitching also means you’ll avoid uncomfortable scratching and prevent chafing. A zipper on the men’s version lets you control your body temperature as you run.

One thing to note is that the men’s version is hoodless but sports the 1/4 zip, great for regulating temperature.

The women’s has a hoodie, but no zipper in the front. Both are made with warm but breathable fabric.

10. Smartwool Merino 150 Short Sleeve

Not every base layer needs to have long sleeves. The Merino 150 has short sleeves so it can be worn alone in summer or as a base layer under warmer gear during the winter.

The soft Merino wool is blended with a nylon core to help increase durability. Plus, flatlock seams allow for added comfort when wearing a backpack or additional layers of clothing. Overall, the shirt is breathable and lightweight.

The fit of the shirt is slim but not constricting. The material is 87% wool and 13% nylon, water-resistant, and comes with natural antimicrobial properties to help reduce odors.