Guides

How much fence do I need?

Fence is bought by the running foot, so the number you want is the distance around the yard, not the area inside it. That distinction is worth more money than any other line on this page.

Perimeter, not area

For a rectangle it is two times the width plus the length:

A 60 by 100 foot lot is 320 feet around. Double the lot to 120 by 200 and the area goes up four times, from 6,000 square feet to 24,000, but the fence only doubles, to 640 feet. Perimeter grows slower than area, which is why fencing a big yard is proportionally cheaper than fencing a small one, and why a long thin lot costs far more to fence than a square one of the same size.

Most yards are not rectangles, and most people are not fencing all four sides. Measure the actual run: the two side lines back to the house, the rear line, and whatever returns to the corners of the building. That is usually a good deal less than the full perimeter.

Posts and panels

Posts go at 6 or 8 foot centres depending on the style. Eight is standard for wood panel and vinyl; six is used for taller fences, windy sites and anything the ground will not hold.

The "plus one" is the part that catches people. A run needs a post at both ends, so ten panels take eleven posts. A closed loop around a yard needs one post per panel, and then every gate breaks the loop and adds two more, because a gate hangs off its own posts and needs a solid one on each side.

Corner and gate posts should be a size up and set deeper. They are the posts that take the load, and a fence fails at its corners long before it fails in the middle of a run.

Gates

Take the gate openings out of the fencing run before you price it, which the calculator above does for you, and then decide on widths honestly:

• 3 to 4 feet for a walk gate. Three is tight with a wheelbarrow.
• 4 feet is the minimum if a mower has to get through, and measure your mower rather than assuming.
• 10 to 12 feet for a double gate wide enough for a trailer, a mini digger, or a truckload of topsoil delivered to the back yard instead of the driveway.

That last one is worth real thought before the fence goes up rather than after. Every future delivery of soil, gravel, mulch or paving either comes through that opening or gets barrowed around the house one load at a time.

Depth and frost

Posts go a third of their above-ground height into the ground, or below the local frost line, whichever is deeper. For a 6 foot fence that is at least 2 feet, and in a cold climate it can be 4.

A post set above the frost line gets pushed up a little every winter as the ground freezes and heaves, and after a few years the fence is visibly wandering. Your local building department publishes the frost depth; it is worth the phone call.

Before you order anything

• Call before you dig. In the US that is 811, free, and a few days ahead. Post holes are exactly deep enough to find a gas line or a buried cable.
• Find the property line properly. Not the neighbour's assumption, not the old fence. Find the survey. A fence built a foot over is a fence you take down.
• Check the setback. Many places require the fence inside the line by some distance, and many limit front-yard fences to 3 or 4 feet while allowing 6 at the back.
• Check the rules that are not the law. A homeowners association may dictate style, colour and which side the rails face; corner lots often have sight-line rules at the junction.
• Talk to the neighbours. A shared line is often a shared cost, and the conversation is much easier before the posts are in.

Ordering

• Measure the run in sections and add them up, rather than measuring the whole perimeter and hoping.
• Add a panel's worth of slack. Ground is never as flat as the plan, and stepped panels on a slope eat length.
• Order corner and gate posts separately. They are a different size from the line posts.
• Budget concrete for the posts: roughly one 50 lb bag per hole for a line post, two for a corner or gate post.

Trace your boundary in the planner

Lay fence as a run along the yard's edge and the planner labels each stretch with its length as you draw it, so the total is measured off the shape your yard actually is rather than the rectangle it is not.