How Much Does a 4x4 Post Weigh
18.37 lb
- Actual size: 3.5" x 3.5" (nominal 4x4")
- Length: 8 ft
- Species: Spruce-Pine-Fir (SPF) (27 lb/ft³ as milled)
Methodweight = (board feet / 12) x density — board feet computed from the ACTUAL, not nominal, dimension.
Moisture content, and any coating/finish weight, will move the real number slightly — this is the dry, as-milled figure.
An 8-foot 4x4 post weighs 18.37 lb — noticeably more than a 2x8 of the same length (16.31 lb) despite looking like a much smaller cross-section, because a square 3.5" x 3.5" post carries more volume than most people mentally estimate from its footprint alone.
Why this one specifically
4x4 posts go vertical — fence posts and deck posts set in concrete or brackets — which is a different handling problem than a joist or stud carried flat: the question behind this lookup is usually how many posts fit in one truck or trailer load, or whether a single person can comfortably set a post by hand without a second set of hands.
What moves the number
This figure is for an 8-foot length; posts are commonly sold longer (10' and 12' are both standard) for buried or bracketed applications, and weight scales linearly with length at a fixed cross-section, so a 12-foot post runs about 1.5x this figure. Moisture content is the other real variable — post stock is sometimes sold pressure-treated and wet, which weighs meaningfully more than the dry SPF reference used here.