How Much Concrete Do You Need for Fence Posts?

Each fence post needs 1-3 bags of concrete (60-lb or 80-lb) depending on post size and hole diameter. A standard 4×4 post in a 10-inch hole needs about 1.5 bags of 80-lb concrete. A 100-foot fence with posts every 8 feet needs 13 posts = about 20 bags.

Concrete Per Post Calculator

4×4 post, 10" hole, 24" deep: 1 bag (80-lb) or 1.5 bags (60-lb). 4×4 post, 12" hole, 30" deep: 2 bags (80-lb). 6×6 post, 12" hole, 30" deep: 1.5 bags (80-lb). 6×6 post, 14" hole, 36" deep: 2.5 bags (80-lb). Gate posts (deeper): add 50% more concrete.

Post Spacing Guide

Standard residential fence: posts every 6-8 feet. Privacy fence (6' tall): posts every 6 feet maximum. Ranch/split rail: posts every 8-10 feet. Chain link: posts every 10 feet. Wind-prone areas: reduce spacing by 1-2 feet. Corner posts and gate posts need extra depth (36" minimum).

How Many Bags for Your Fence

50-foot fence (8' spacing): 8 posts = 12 bags (80-lb). 100-foot fence: 14 posts = 21 bags. 200-foot fence (full yard): 27 posts = 40 bags. Add 2 bags per gate opening (extra for gate posts). These estimates use standard 4×4 posts with 10" holes at 24" depth.

Setting Posts in Concrete

Dig holes 3x the post width and 1/3 of total post length deep. Set post, brace plumb, pour dry concrete mix into hole, add water per bag instructions. Fast-setting concrete sets in 20-40 minutes. Standard concrete takes 24-48 hours. Don't fill hole to the top — leave 2-3" for soil to grade away from post.