Wood Fence Post Calculator
Get the number of posts and the length of 4×4 or 6×6 to buy — sized for your fence height plus the part that goes in the ground, so nothing comes up short.
↺ Filled in from the fence in your last calculation. Edit anything below.
How many fence posts — and how long?
Two numbers decide a post order, and this calculator handles both. The count is your run divided by the post spacing, plus one for the post that closes the last section: a 100-foot run at 8-foot spacing is 13 sections, so 14 posts. Add a post for every corner and each side of a gate.
The length is the part people underestimate. A post has to reach from the bottom of its hole to the top of the fence, so it spans the buried depth plus the height above ground. Set a 6-foot fence 2 feet deep and each post must be 8 feet — which is why the calculator recommends the shortest standard stock (8, 10, 12 or 16 ft) that covers your required length.
Why the post is taller than the fence
- Burial depth comes first: at least one-third of the above-ground height, and always below the frost line so the post doesn't heave in winter.
- Stock lengths jump in 2-foot steps. An 8-foot fence set 2.5 feet deep needs 10.5 feet of post — so you buy 12-foot stock and trim, not 10-foot that leaves you short.
Corner, end and gate posts
These carry more load than a line post. Many builders step them up to 6×6, set them deeper, and use more concrete. Once you know the post count here, run it through the fence post concrete calculator for the exact number of bags, and see the post depth guide and post spacing guide for the why behind the numbers.
Estimates only — follow your local code for post depth, spacing and permits.
Frequently asked questions
How many posts do I need for my fence?
Divide the total run by your post spacing and add one for the closing post. A 100-foot fence at 8-foot spacing needs 100 ÷ 8 = 12.5, rounded up to 13 sections, so 14 posts. Corners and gates each add a post beyond that straight-run count.
What length post do I buy for a 6-foot fence?
The post has to cover the height above ground plus the part buried in the ground. A 6-foot fence set 2 feet deep needs an 8-foot post — so an 8-foot 4×4 lands flush with the top. Set it deeper, or want the post to stand proud of the pickets, and you step up to a 10-foot post.
How deep should a wood fence post be buried?
Set posts at least one-third of the above-ground height into the ground, and always below your local frost line. For a 6-foot fence that is roughly 2 to 2.5 feet. Corner, end and gate posts should go deeper because they carry more load.
Should I use 4×4 or 6×6 posts?
4×4 posts are the standard, economical choice for residential fences up to 6 feet. Step up to 6×6 for taller or heavier privacy fences, for gate and corner posts, or anywhere you want extra stiffness and a longer service life.