So where does 835 feet come from?

It is the perimeter of a square acre: the square root of 43,560 is 208.7, and four sides of that is 834.8 ft. It is a correct answer to a question about a square, presented as an answer about an acre.

How do I know my lot ratio?

Divide the longer boundary by the shorter one. A 120 × 360 ft lot is 3:1. Your plat map or county assessor record has the dimensions; you do not need to measure to know the ratio.

What if my lot is not a rectangle?

Then measure each boundary and add them. Any irregular shape has a longer perimeter than the rectangle of the same area, so a rectangular estimate is a floor, not a ceiling.

Is fencing an acre a realistic DIY job?

It is a large one. At 8 ft spacing an acre is roughly 105 to 120 post holes, each needing digging, setting and bracing. Most people who do it hire the post setting and build the panels themselves.

Fence Ledger

How much fencing do I need for 1 acre?

Search this and you will be told 835 feet. That number is correct for exactly one lot shape: a perfect square, 208.7 ft on each side. Very few properties are that.

If the lot is square

835 ft of fence

Most lots are not square. The table below shows what the other shapes need.

What the usual answer misses

An acre is always 43,560 square feet, but its perimeter is not a property of its area — it is a property of its shape. A 3:1 lot of the same acre needs 964 feet, which is 129 feet more than the popular answer. At installed prices that is a four-figure difference on the single question homeowners ask most.

Same acre, five shapes

Fence needed for 1 acre at five lot shapes
Lot shape	Dimensions	Fence needed	Extra vs. square
SquareThe shape the usual answer assumes.	209 × 209 ft	835 ft	the usual answer
3:2Slightly deeper than wide — common on newer plots.	170 × 256 ft	852 ft	+17 ft$430–947 installed
2:1A typical suburban lot.	148 × 295 ft	885 ft	+51 ft$1,266–2,785 installed
3:1Deep and narrow, common in older subdivisions.	120 × 361 ft	964 ft	+129 ft$3,229–7,103 installed
4:1A long strip — a flag lot or an infill plot.	104 × 417 ft	1,044 ft	+209 ft$5,218–11,479 installed

Cost column uses the site's verified installed range of $25–55 per linear foot for wood privacy fence. Ranges are national planning figures, not quotes.

Work out your own

Every assumption above is editable. Change the length, the spacing, the hole size — the numbers and the working update as you go.

Units

Shape

Fence length

Height

Gates

Advanced options

These are typical values, not requirements. Post depth in particular is governed by your local frost line and building code — check before you dig.

Post spacing

Gate width

Picket gap

Hole diameter

Hole depth

Gravel base

Bag yield

Waste allowance

Posts

106

Sections

104

Pickets

1,909

Concrete

177 bags

Estimated cost

Materials only (DIY)

$6,880 – $17,300

Professionally installed

$21,075 – $46,525

National planning ranges compiled from published US construction cost guides, last checked September 2026 (confidence: medium-low). Prices vary sharply by region, season and contractor. These are estimates for planning, not quotes.

Sources: homeguide.com, calcsummit.com, angi.com, ergeon.com, homewyse.com

Shopping list

Bill of materials for this fence
Material	Size	Quantity
Posts	4x4	106
Rails incl. waste	2x4	344
Pickets incl. waste	1x6	1,909
Concrete mix		177bags
Gravel		39bags
Exterior screws		≈12,300
Walk gate kit		1

Why these numbers

How we got the section count

Run 1: 831 ft ÷ 8 ft = 103.88, rounded up to 104 sections

How we got the post count

3 posts are fixed by the shape itself
2 at the open ends
1 carrying a gate
103 line posts spaced between them
106 posts in total

How we got the picket count

Each picket covers 5.5 in plus a 0.25 in gap, so they repeat every 5.75 in
831 ft of fence needs 1,735 pickets
Plus 10% for offcuts, rounded up to 1,909

How we got the concrete

Each 10 in hole is 30 in deep, less 4 in of gravel base, leaving 26 in of concrete
The 4x4 post itself takes up part of that, so each hole needs the remainder
Across 106 posts
Divided by the 0.6 cu ft a bag yields: 176.21, so buy 177 bags

Common questions

So where does 835 feet come from?: It is the perimeter of a square acre: the square root of 43,560 is 208.7, and four sides of that is 834.8 ft. It is a correct answer to a question about a square, presented as an answer about an acre.
How do I know my lot ratio?: Divide the longer boundary by the shorter one. A 120 × 360 ft lot is 3:1. Your plat map or county assessor record has the dimensions; you do not need to measure to know the ratio.
What if my lot is not a rectangle?: Then measure each boundary and add them. Any irregular shape has a longer perimeter than the rectangle of the same area, so a rectangular estimate is a floor, not a ceiling.
Is fencing an acre a realistic DIY job?: It is a large one. At 8 ft spacing an acre is roughly 105 to 120 post holes, each needing digging, setting and bracing. Most people who do it hire the post setting and build the panels themselves.