Fence Calculator

How to use the fence calculator

Walk the fence line with a long tape or a measuring wheel and enter the total run in feet, adding every side you intend to fence into one number. Stake the line and pull a string before you measure: measuring along a string is how you get an honest length across a sloped or gently curved yard, where a tape laid on the ground consistently reads long.

Then count gates and, under Advanced, corners. A gate replaces a panel but keeps its posts, and a corner ends one straight run and begins another, which costs an extra post without buying you any extra section.

Post spacing drives the whole bill of materials, and for most residential fences the panels decide it for you rather than the other way round. Prefab panels and rail kits come in fixed widths, the posts have to land on their ends, and an 8 ft panel therefore means 8 ft spacing, full stop.

Where you genuinely have a choice — building stick-style with rails and pickets — 8 ft is the economical standard and 6 ft buys stiffness, because shorter spans flex less in wind and sag less under wet pickets.

Other fence types set their own conventions: UGA Extension puts line posts 10 to 12 ft apart for most farm fences, and ASTM F567 caps chain-link line posts at 10 ft. None of those transfer to a tall privacy fence, which behaves like a sail.

Read the three outputs as three different shopping lists. Posts is the dig-and-set number: it drives how many holes you auger, how much concrete you carry, and how long the weekend gets.

QUIKRETE states that two 50 lb bags of its fast-setting mix will set a 4-inch post in a 10-inch hole 2 feet deep, so multiply that by your post count before the store run, and expect more for the bigger, deeper holes that corner and gate posts want.

Panels is what goes on the cart, and gates ride along as prefab units or hardware kits. Buy panels last if your run has a remainder, because a 100 ft run at 8 ft spacing ends in a 4 ft section that most people fill by cutting one panel down rather than ordering a custom width.

How deep should the posts be set?

Depth is where fences are won or lost, and it is the one figure this calculator deliberately will not give you. The carpentry convention is to bury a third of the post length, which is why a 6 ft privacy fence is built from 8 or 9 ft posts.

Extension guidance runs in the same direction: UGA Extension says wooden line posts should be set at least 2 ft deep and preferably deeper, with deeper settings in sand or wet soil, while Penn State Extension gives a typical line post depth of 36 inches and notes that corner and gate posts are about 25 percent larger in diameter and often go to 48 inches.

Penn State also names the failure mode directly — soils heave with frost and loosen posts that are not set deep enough. Your required depth relative to the frost line is a local code figure, so ask the building department before you buy posts.

The formula, worked line by line

A fence is the classic off-by-one problem dressed in cedar. Divide the run by the post spacing and round up, because a leftover 3 ft of yard still needs a section to close it, and you now have your section count.

Then add one, because a line of N sections is bounded by N + 1 posts: every section needs a post at each end, and every internal post is shared by the two sections either side of it. Miss that final post and the last panel has nothing to hang on.

Corners and gates then pull in opposite directions, which is why they are separate inputs. A corner is where one straight run stops and another begins, so it needs its own post but adds no section — one extra post, one extra hole, no extra panel. A gate is the reverse: it occupies a section that a panel would otherwise have filled, hanging between the same two posts, so it removes a panel and leaves the post count untouched.

sections = total length ÷ post spacing, rounded UP
posts = sections + 1 + corners
panels = sections − gates   [never below 0]

Corners are worth walking through because they surprise people. Take a 60 by 40 ft rectangle you want fully enclosed: the run is 200 ft, which at 8 ft spacing is 25 sections. On a straight line that would be 26 posts, but a closed rectangle has four corners, and adding four gives 30.

Fence an L-shaped side yard instead, with one corner, and 200 ft comes to 27 posts. The corner count is not cosmetic — each one is a post that carries pull from two directions at once and is normally upsized and set deeper for exactly that reason.

Two things this arithmetic cannot decide for you, both local. The first is depth: frost depth is a county-level figure enforced by your building department, and a footing that is fine in Georgia will heave out of the ground in Minnesota.

The second is whether you are allowed to build the fence at all in the position you have staked — height limits, setbacks from the property line, corner-visibility triangles, and permit requirements vary street by street, and a survey pin is a much cheaper way to find your boundary than a neighbour with a tape measure. This is a materials estimate, not a plan set.

Questions people ask