Estimate fence materials — posts, rail sections, and pickets — from your fence length, post spacing, and picket width.
posts = ceil(length ÷ spacing) + 1; pickets = length_in ÷ (picket_w + gap)
Posts are spaced 6–8 ft apart with one extra at the end. Pickets are counted by fence length divided by picket width plus gap.
Use the concrete calculator to estimate bags for setting each post.
For a 100 ft fence with posts every 8 ft: 100 ÷ 8 = 12.5, rounded up to 13 sections, needing 14 posts (one extra for the final end). With 2 rails per section that's 26 rails. For pickets at 5.5 inches wide with a 0.25-inch gap: 100 ft is 1,200 inches, divided by 5.75 inches per picket = about 209 pickets.
Each post should be set in concrete — figure one to two 50 lb bags of concrete per post depending on post and hole size, so 14 posts is roughly 20-28 bags. Use the concrete calculator to confirm based on your hole dimensions.
Counts are geometric. Picket width and gap vary by style — a standard dog-ear picket is 5.5″ wide.
Typically 6 to 8 feet on center for wood fences.