Post Hole Calculator
Calculate concrete needed for fence post holes. Enter hole diameter, depth, post size, and number of holes for total bags needed.
π³οΈ Post Hole Calculator
Results
Concrete per Hole1.37 cu ft
Total Concrete13.74 cu ft
Total Concrete0.51 cu yd
60 lb Bags31 bags
80 lb Bags23 bags
π‘ How to Calculate Concrete for Post Holes
Post hole concrete volume equals the hole volume minus the post volume: Ο Γ (hole radius)Β² Γ depth β Ο Γ (post radius)Β² Γ depth. Standard fence post holes are 10 inches diameter Γ 36 inches deep for a 4Γ4 post. Deck post holes are typically 12 inches diameter Γ 42β48 inches deep.
Each 80 lb bag of concrete yields approximately 0.6 cubic feet. Quick-set concrete can be poured dry into the hole and wetted β no mixing required. For structural posts (decks, pergolas), use standard concrete mix and allow full cure time (24β48 hours before loading).
10 fence post holes, 10" diameter Γ 36" deep with 4" posts: concrete per hole β 0.15 cu ft. Total = 1.5 cu ft β 3 bags of 80 lb concrete. For 12" holes, it's about 5 bags total.