How to Calculate the Materials for a Fence
I built this fence calculator to help you estimate posts, rails, and pickets before you buy. Getting the material count right before you start saves multiple trips to the hardware store and ensures your fence looks uniform from end to end. The key variables are total fence length, post spacing, fence height, and picket width — this calculator handles all of them and gives you a complete materials list.
The standard approach is to divide your total fence length by your post spacing (typically 6–8 feet) to get the number of bays, then add one post for the starting end. Each bay needs two horizontal rails (for a basic 6-foot privacy fence) or three rails (for added rigidity). The picket count comes from dividing the bay width by the picket width plus gap. Always add 10% to your picket count for waste from cuts at corners and gates.
Post Spacing and Depth Guidelines
Post spacing and burial depth are the two most common fence mistakes that lead to failure. Here's what I recommend:
- 6-foot privacy fence: space posts no more than 8 feet apart; bury at least 2 feet (one-third of total post length).
- Areas with high wind or sandy soil: reduce spacing to 6 feet and bury posts 30 inches deep.
- Gate posts: always use 4" × 6" or 6" × 6" posts for gates — the extra leverage from a swinging gate requires more post mass and deeper burial.
- Frost heave regions: dig posts below the frost line, which varies from 12" in the South to 48"+ in Minnesota and Canada.
Wood vs. Vinyl vs. Metal Fencing
Cedar and redwood are the premium wood choices — naturally rot-resistant and beautiful when stained. Pressure-treated pine costs less and lasts well when sealed, but requires more maintenance. Plan to re-stain or re-seal a wood fence every 2–3 years to prevent greying and cracking.
Vinyl fencing costs more upfront but is virtually maintenance-free — no painting, staining, or sealing ever. It won't rot, rust, or warp. The downside is that vinyl can become brittle in very cold climates and doesn't handle impact as well as wood. For a low-maintenance fence in a moderate climate, vinyl is often the better lifetime value. Metal (aluminum or steel) is ideal for decorative and security applications and lasts decades with minimal upkeep.
Frequently Asked Questions
How much concrete do I need for fence posts?
For a standard 4" × 4" post in a 10-inch diameter hole, one 50 lb bag of fast-setting concrete per post is typically enough for a 3-foot deep hole. For 6" × 6" posts or holes deeper than 3 feet, use two bags per post. Fast-setting concrete (Quikrete Fast-Setting or equivalent) is ideal for posts because you pour it dry, add water, and it sets in 20–40 minutes without mixing.
Do I need a permit to build a fence?
Many municipalities require a permit for fences over 6 feet tall or for any fence along a front property line. HOAs often have additional restrictions on fence height, material, and colour. Always check with your local building department and HOA before purchasing materials. Property surveys are also important — building a fence on your neighbour's property, even by a few inches, can create legal disputes that are expensive to resolve.
How do I fence on a slope?
There are two approaches: stepped fencing and racked (contoured) fencing. Stepped fencing keeps each panel horizontal with gaps underneath at the low end of each step — better for privacy with large grade changes. Racked fencing follows the slope continuously, which looks cleaner on gradual slopes. Racked fence panels must be built on-site or purchased as rackable panels — standard pre-built panels cannot be racked without damaging the picket-to-rail connection.
