Post Base Calculator

Size the post-base hardware for a deck or pergola in one step. Enter the number of posts and the base style to get the bases needed and the total anchor bolts or screws to order.

ConcretePost1 in. gap
Post Bases Needed
bases
One base per post.

Usage Tip

Standoff bases keep end grain off concrete and extend post life. Order a few extra fasteners — many brackets ship without them.

THE MATH
Bases = Posts
Fasteners = Posts × F
Post count = Posts
F = fasteners per base: 4 for standoff bases, 2 for wet-set bases.
Posts = number of structural posts entered.
Standoff bases lift the post on a raised pedestal so end grain never sits on the slab — keep a 1 in. minimum gap so water drains and the post resists rot.
Wet-set bases are embedded in the wet pour and rely on the concrete to hold, so they take fewer fasteners; set and brace them plumb before the mix sets.
Match the connector and fastener size to the base model and local code, and use only hardware rated for exterior use or contact with treated lumber.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.