> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# CFS Stud/Column Calculator: Understanding the Support Model
> Why the Calcs.com CFS Stud/Column calculator uses a cantilever model, how that explains a 4x moment mismatch, and when to switch to CFS Beam.
The Calcs.com **Cold-Formed Steel (CFS) Stud/Column** calculator uses a fixed analysis model: it treats the member as a **cantilever, fixed at the base and free at the top**. This is intentional and matches its purpose: a concentrically loaded stud or column standing up from a base connection with no restraint at the top.
If you enter a uniform lateral load *w* (for example, wind) over the member height *L*, the maximum moment the calculator reports will be **M = wL²/2** at the base, not the **wL²/8** you get from a pinned-pinned simple span. That is a factor of 4 difference, and it is the most common reason a hand calc on a braced curtain-wall stud disagrees with the CFS Stud/Column results.
## When the CFS Stud/Column calculator is the right tool
Use it when the member genuinely acts as a cantilever: fixed (or effectively fixed) at one end, free at the other, carrying axial load through its centroid with lateral load applied along its length. The base fixity and free top are baked into the analysis. You cannot switch them to pinned/roller inside this calculator.
## When to use the CFS Beam calculator instead
A typical curtain-wall stud sits between a bottom track and a deflection track. It is braced top and bottom for out-of-plane wind, which is a **pinned/roller simple-span** condition, not a cantilever. For that case, use the **CFS Beam** calculator instead:
1. Open the **CFS Beam** calculator.
2. Set the **supports** to **pinned/roller**.
3. Set the **span** equal to the stud height.
4. Apply the lateral (wind) load along the span as you normally would on a beam.
The reported peak moment will then be **wL²/8**, matching the hand calc for a simply supported stud.
This is a modeling choice, not a units or input bug. If your CFS Stud/Column result looks about 4x higher than expected under lateral load, the mismatch is almost always **cantilever vs. simple-span**. Check which support condition actually applies to your member before adjusting inputs.
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