Calculators/ Framing & Exterior/Gate Post Calculator
Gate Post Calculator
Post size, depth and concrete for a gate.
Gate Post Calculator
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Gate posts do a much harder job than fence posts: a gate hangs off one side and tries to lever the post out of the ground every time it swings. Depth and diameter both need to go beyond the fence standard.
How this is calculated
- Depth starts at a third of the gate height and adds an allowance for width, because a wider gate applies more leverage. Minimum 2.5 feet.
- Hole diameter of 12 inches is a practical minimum for a gate post, against 10 for a plain fence post.
- Post length = embedded depth + gate height + a few inches of clearance below the gate.
Frequently asked questions
Why do gate posts sag?
Almost always an undersized or shallow hinge post. The gate's weight acts through a lever arm equal to the gate width, and the post slowly rotates in the ground.
Should I use 4x4 or 6x6 for a gate?
6×6 for anything over about five feet wide or for a solid privacy gate that catches wind. 4×4 is fine for a light garden gate.