Fence post concrete calculator
Number of posts
posts
Post size
4×4 (3.5 × 3.5 in)
6×6 (5.5 × 5.5 in)
Round, 3 in
Round, 4 in
Hole diameter
in
About 3× the post width
Hole depth
in
⅓–½ of the post's height above ground
Gravel at the bottom
in
For drainage under the post
Extra for waste
%
Holes are rarely perfectly round
You'll need
Free calculator by Backyard Numbers ↗