Are 4x4 Posts Strong Enough for a Pergola?
- Bjørn Content Team
- May 22
- 2 min read
If you’re planning to build a pergola in your backyard, you’ve probably asked yourself this question: Are 4x4 posts strong enough to support a pergola? The short answer? Absolutely—however, your use case may push you in the direction of 6x6 brackets. Let’s break it down so you can build confidently (and safely) whether you're using 4x4 brackets or 6x6 pergola brackets.
The Case for 4x4s
4x4 posts are considered a great size for pergola construction. In light-duty builds—like smaller, freestanding shade structures or those attached to an exterior wall—4x4s can absolutely do the job, especially if your structure isn't supporting heavy accessories like hanging swings or other focused loads.
DIY experts & builders alike report using 4x4s successfully in environments where shade and a simple roof are the priority. Roofing can also be applied to a 4x4 structure, especially when using shorter spans and multiple posts for added support. However, 4x4s are slightly more prone to twisting, bowing, or flexing over time—especially if your pergola is exposed to strong wind or uneven ground.
Benefits of 6x6's
For peace of mind and long-term durability, many builders recommend upgrading to 6x6 posts. 6x6s are a bit better suited for outdoor structures exposed to the elements, especially those needing to endure heavy wind, weight, or movement. They're also more stable in the ground and less likely to warp.
Upgrading to 6x6s means fewer worries about movement or failure—and a longer-lasting pergola that feels solid no matter the season.
How Bjorn Woodworks Brackets Come In
At Bjorn Woodworks, we’ve designed pergola bracket kits that are compatible with both standard 4x4 and 6x6 lumber, giving you flexibility to choose what’s best for your project. Each bracket has a minimum of 3k shear weight capacity, giving you flexibility for larger builds that you'd like to last. If you do opt for 4x4 posts, we recommend:
Keeping spans under 12 feet or under
Using corner gusset brackets to help further prevent wobble for taller builds
Anchoring your concrete or footings securely
Avoiding using heavy accessories (like swing seats)
That said, both 6x6 and 4x4 offer almost the same benefits so both sizes are great for your build, it more depends on what features you'd like your build to include.
Final Verdict
So, are 4x4 posts strong enough for a pergola? Definitely, especially for smaller, simpler builds. But if you're looking for a more durable, long-term setup that can handle heavier roof loads, privacy walls, or hanging accessories, 6x6 posts may be the better choice for you
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Whichever route you take, Bjorn Woodworks pergola bracket kits can help you get the job done right—with clean lines, rock-solid stability, and DIY simplicity. Ready to start building? Check out our Pergola Kits to create a structure that’s strong, stylish, and ready for anything.
