The Short Answer
A flannel should feel comfortable without looking oversized. The right fit depends on how you plan to wear it.
Fit Scenario 1: Wearing It as a Shirt
For a standalone flannel, start with your usual size.
Look for:
- Shoulder seams sitting at the edge of your shoulders
- Enough room across the chest to move comfortably
- Body length at or just below the hip
- Sleeves ending around the wrist
Rule of thumb: Get the shoulders right first. A little extra room through the chest and body is manageable, but poorly fitting shoulders are much harder to fix.
Fit Scenario 2: Wearing It as an Overshirt
Wearing a flannel open over a T-shirt calls for a slightly more relaxed fit.
Look for:
- Your usual size for a cleaner fit
- One size up for a more relaxed look
- Enough room across the chest for your base layer
- No bunching around the shoulders
The sweet spot: Relaxed, not shapeless.
Fit Scenario 3: Wearing It Under a Jacket
When layering under a work jacket, denim jacket, or shell, avoid too much bulk.
Look for:
- Your usual size
- Sleeves that don’t bunch inside the jacket
- A comfortable but slightly closer fit through the torso
Pro tip: Lightweight and midweight flannels work especially well under jackets. Heavyweight flannels are better as the outer layer.
Fit Scenario 4: Wearing It Over a Hoodie
A flannel worn over a hoodie needs extra room.
Look for:
- One size up, depending on hoodie thickness
- Enough chest room to button comfortably
- Sleeves wide enough to fit over the hoodie
Avoid a fit that pulls tightly across the chest — it will restrict movement and look forced.
Fit Scenario 5: The Flannel Shirt Jacket
A shacket is designed to work more like a lightweight jacket than a traditional shirt.
Look for:
- Your usual size if the shacket is designed for layering
- One size up only if you want extra room for a sweatshirt or hoodie
- Room for a T-shirt or sweatshirt underneath
- Shoulders still sitting naturally at the edge
- A length around the mid-hip
The extra room should feel intentional, not oversized.
Should You Size Up in Flannel?
| How You Wear It | Starting Point |
|---|---|
| Standalone shirt | True to size |
| Open overshirt | True to size or +1 |
| Under a jacket | True to size |
| Over a hoodie | +1 |
| Shacket | True to size or +1 depending on layering |
If you’re between sizes, consider sizing up when you plan to layer. For a standalone shirt, your usual size is generally the best starting point. Fabric weight can affect how a flannel feels when layered, but weight alone isn't a reason to size up. Check the garment measurements and consider sizing up only if you plan to wear thicker layers underneath.
Always check the measurements for the specific style before ordering.
Find Your Fit
The best flannel is the one that fits the way you actually wear it.
Check our Size Guide for measurements and find the FlannelGo style that works for your everyday layers.
