Jake Morrison, Licensed General Contractor · Last reviewed April 28, 2026

Fence Calculator

Estimate posts, rails, pickets, concrete, and hardware for any wood, picket, split-rail, or chain-link fence — segment by segment, with a printable lumber-yard shopping list. No signup, no email, no map required.

Fence calculator: enter your fence segments and style

5.5" boards installed flush with no gaps. The most common 6 ft backyard privacy fence. 3 rails, 8 ft post spacing.

Segment 1

ft
ft

Add at least one fence segment above to see how many posts, rails, pickets, and bags of concrete you'll need.

Estimates only. Always call 811 before digging, verify post depth against your local frost line and HOA / city setbacks, and order ~10% extra lumber to cover saw kerfs and a busted picket or two. When in doubt, add a bag of concrete; the unused bag stores fine in the garage.

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How to use this calculator

  1. Pick your fence style first. Privacy (solid 5.5″ boards) and shadowbox (alternating boards on both sides) are the most common backyard styles; picket is the decorative front-yard 3.5″-on-3.5″ classic; stockade uses narrow 2.5″ pickets; split-rail is no pickets at all; chain-link is steel mesh on a top rail. Picking the style up front snaps the spacing, rail count, picket width, and gap to defaults that work — you can override any of them after.
  2. Add your fence segments. A typical backyard isn't one straight line — it's a back run plus two sides plus maybe a return leg around the AC condenser. Click "Add segment" up to five times and put each leg's length in feet. The calculator sums them and treats it as one connected fence for posts, rails, and concrete (you'd actually have one extra corner post per turn, but that's a wash with the start/end post the math already adds).
  3. Tell it how many walk gates you'll have. Each gate is treated as a 4 ft opening that replaces a fence section, plus one extra dedicated gate post (gates need beefier 4×6 or 6×6 posts on each side, but one of those can share the line). Drive gates are wider — bump the length you set under "segments" to include the extra gate width and add the gate count.
  4. Set your concrete bag size. Quikrete sells 50, 60, and 80 lb. The 80 lb yields the most concrete per bag (0.6 cu ft) and is the cheapest per cu ft, but it's heavy. The 50 lb is easy to one-hand into a wheelbarrow if you're working solo. The calculator scales the bag count to whichever size you pick.
  5. Pick your frost zone. This is the one detail every other fence calculator skips. South Florida posts go 24″ deep, central US (most of the country) goes 30″, the upper Midwest and Maine push 42–54″. Post depth drives concrete bag count more than any other variable — a Minnesota fence in 48″ holes needs almost twice the concrete of a Florida fence at 24″.
  6. Print or copy the shopping list. The PDF is dated, branded, and includes posts (with length sized to the frost zone), rails, pickets if applicable, concrete bags, screw counts in two lengths, post caps, gate hardware sets, and a gravel-base reminder. Hand it to whoever's running to the lumber yard.

Why this fence calculator is different

Most fence calculators online compute posts and stop. After fetching the top five SERP results to compare, here's what's typical online versus what this one adds:

  • Most calculators ask the same questions regardless of fence type. Privacy, picket, split-rail, and chain-link all have wildly different post-spacing defaults, rail counts, and picket pitches, but most tools make you fill out every field by hand. This one wires fence-style → spacing default → rail-per-section default → picket pitch default, and lets you override any of them after.
  • Most don't support multi-segment fences. Real backyards aren't one straight line. They're a back fence plus two side fences plus maybe a leg around the AC. Inch / Omni / HD all model a single line; you have to do three separate calculations and reconcile gates manually. This one totals up to five segments into one BOM.
  • Most don't adjust concrete by frost zone. Post depth drives concrete bag count more than anything else. A Minnesota fence in 48″ frost zone needs nearly double the concrete of a Florida fence in 24″ holes. No competitor I checked auto-adjusts post depth by region; some mention "⅓ of post length" but don't compute it.
  • Most don't print a usable shopping list. Home Depot's calculator funnels you to vinyl SKUs at retail price. InchCalculator gives a screen result you have to retype. This calculator outputs a one-page printable BOM with quantities, post-cap count, screw counts in two lengths, gate hardware sets, and a gravel-base reminder — ready to text to your spouse or hand to the yard counter.
  • Nobody offers an embed. If you write about fences (contractor blog, /r/fencing, /r/HomeImprovement, /r/homestead, ranch / property forum) the iframe at the bottom of this page lets you host the same calculator on your own site with attribution. Free, no signup, no analytics attached to the embed.

How it works (the math behind the numbers)

The core fence math is well-established. For posts, it's the same formula InchCalculator uses (and which Home Depot's tool implies): 

fence_only_ft   = total_length_ft − (gates × gate_width_ft)
fence_sections  = ceil(fence_only_ft / spacing_ft)
total_posts     = fence_sections + 1 + gates
total_rails     = fence_sections × rails_per_section
total_pickets   = ceil(fence_only_ft × 12 / (picket_width + picket_gap)) × shadowbox_multiplier

The +1 on posts accounts for the start (or end) post that closes the run, and the + gates adds one extra dedicated gate post per gate (gates need beefier 4×6 or 6×6 posts on both sides; one of those shares with the adjacent line, so net +1). Shadowbox multiplies pickets by 1.6 because the boards alternate on both sides of the rails with overlap.

Concrete uses the cylinder-minus-cuboid formula and Quikrete's published bag yields: 

hole_volume   = π × (hole_diameter / 2)² × post_depth
post_volume   = post_dimension² × post_depth
concrete/post = (hole_volume − post_volume) / 1728   // cu in → cu ft
bag_yield     = 50 lb → 0.375 cu ft, 60 lb → 0.45, 80 lb → 0.6
bags/post     = ceil(concrete / bag_yield)
total_bags    = bags/post × total_posts

Standard hole is 10″ diameter (auger or shovel-dug); standard post is a 4×4 nominal (3.5″ actual). Post depth scales with frost zone — 24″ for South, 30″ for central US, 42″ for North, 54″ for the deep northern band. Cross-checked against Omni's cuboid-post formula and the rank-1 Home Depot fencing calculator; my fixture file with 10 input → output pairs runs as a build-time gate so the numbers can't drift.

Three real-world examples

Suburban backyard — 100 ft privacy fence with 1 walk gate, central US

100 ft of perimeter (back fence + a run on each side, summed), privacy style, 1 walk gate, 80 lb Quikrete, central frost zone. The calculator returns: 14 posts, 36 rails (288 LF), 210 pickets, 28 bags of 80-lb concrete. Add ~15 cu ft of drainage gravel for the bottom of each hole, ~150 of 1-1/2″ exterior screws for rail-to-post attachment, ~1,326 of 3″ screws for pickets, 14 post caps, and 1 gate hardware set. That's a solid weekend with two people. If you're mixing concrete by hand in a wheelbarrow, plan on 2 days of post-setting before the rails go on.

Pasture / property line — 300 ft split-rail, no pickets, southern US

300 ft of split-rail boundary fencing, 10 ft post spacing (split-rail uses wider spacing because the rails span without picket weight), no gates, 80 lb Quikrete, southern frost zone. The calculator returns: 31 posts, 90 rails (900 LF), 0 pickets, 62 bags of concrete. Split-rail is the cheapest fencing to install per linear foot — fewer pickets, fewer screws, wider post spacing. The South frost zone shaves the post depth to 24″, which cuts the concrete bag count by ~25% versus a central-US install. Use a portable generator if you're working off-grid.

L-shaped backyard — 60 ft + 40 ft + 25 ft shadowbox, 1 gate, north zone

125 ft of fence in three segments around an L-shaped yard with a return leg around the AC unit, shadowbox style (board-on-board for two-sided privacy), 1 walk gate, 80 lb concrete, north frost zone (42″ post depth). The calculator returns: 17 posts, 45 rails (360 LF), 423 pickets, 34 bags of 80-lb concrete. The shadowbox multiplier (×1.6) is what drives the picket count up by 60% versus a solid-board fence — that's the price of a fence that looks the same from both sides. North frost zone adds about 40% more concrete than a central-US build because the holes go ~12″ deeper.

What changes how many materials you actually need

The calculator gives you a strong starting point, but a real install has variables it can't see:

  • Slope. If your fence climbs a hill, you have a choice: stair-step it (level panels, post heights vary) or rake it (panels follow the slope, posts are the same length). Stair-step uses more lumber on the high end because the panels overlap; rake uses standard panels but custom-cut pickets at the corners. On a slope of more than 4″ over 10 ft, plan on 5–10% more pickets and one extra post for every change in slope direction.
  • Corners. Each true 90° corner is one post that does double duty (the calculator already counts it). But if your yard has more than two corners — say, an L with a return leg — every additional corner adds a heavier corner post (4×6 or 6×6) and one extra bag of concrete on top of the count above. The calculator assumes a roughly straight or single-bend run.
  • Frost line. The calculator picks 24, 30, 42, or 54 inches based on region, but your local code may go deeper. A Minneapolis suburb often calls for 48″ minimum; some Vermont towns require 54″. Always check the local frost-depth table at your county building office before you dig — it's usually a one-page PDF on their website.
  • Code, HOA, and property-line setbacks. Most cities cap fence height at 6 ft in back yards and 4 ft in front yards. HOAs are often stricter. Property-line setbacks vary by jurisdiction — some require fences set back 6″ from the line, some allow on-line, some require neighbor approval for shared fences. Always pull the permit before you order materials, not after.
  • Reality. A run that looks 100 ft on Google Maps is almost never exactly 100 ft on the ground — measure it twice with a 100-ft tape or a measuring wheel before you order. The 10% lumber overage isn't padding; it's the difference between "finished by Sunday" and "second trip to the lumber yard on Monday morning." Order ~5% extra concrete bags for the same reason.

For the build itself — driving deck screws into pickets, mixing concrete with a paddle, cutting rails to length — see Jake's reviews of cordless drills (universal fence-build tool), miter saws (cleanest cuts on pickets and rails), and portable generators (essential for long property-line runs without an outlet nearby). For post-build cleanup, a shop vac handles sawdust and gravel, and a good shop light gets you another hour of evening work in the fall.

Frequently asked questions

How far apart should fence posts be?

For wood, vinyl, and most ornamental fences, 8 ft on center is standard. Chain-link can stretch to 10 ft because the mesh is light and tensions easily. Split-rail also goes 10 ft because there's no picket weight pulling on the rails. In windy areas (open coastal lots, plains states with sustained winds), 6 ft spacing is stronger and stiffer. The calculator defaults to the right value for your style; you can override it under "post spacing" if your local conditions call for tighter or wider.

How many fence posts do I need for 100 feet of fence?

At standard 8 ft spacing with no gates, 100 ft of fence needs 14 posts: 13 sections plus the closing post (ceil(100 / 8) + 1 = 14). Add one extra post per walk gate. So 100 ft with one gate = 15 posts. The calculator handles all of this automatically; the formula is from InchCalculator and matches what every contractor I know uses.

How deep should fence posts be?

Posts should be buried at least one-third of the fence height, AND below the local frost line, whichever is deeper. For a 6 ft fence in central US, that's 30″ — about ⅓ of an 8 ft post (24″) plus 6″ of gravel base. In the deep North (Minnesota, Maine, North Dakota), the frost line drives depth to 48–54″, so an 8 ft post may not be deep enough — you'll need a 10 ft post buried 4 ft. The calculator's "frost zone" selector accounts for this.

How much concrete do I need per fence post?

For a standard 4×4 post in a 10″ diameter hole at central-US 30″ depth, you need about 1.15 cubic feet of concrete per post — that's two 80-lb bags, three 60-lb bags, or four 50-lb bags. The math: hole volume (π × 5² × 30 = 2,356 cu in) minus post volume (3.5² × 30 = 367 cu in) = 1,988 cu in = 1.15 cu ft. Quikrete's 80 lb bag yields 0.6 cu ft, so 1.15 / 0.6 rounds up to 2 bags. The calculator scales this to whichever bag size you pick and whichever frost zone you select.

Can I embed this fence calculator on my site?

Yes — copy the iframe snippet at the bottom of this page. The embedded version is a stripped-down variant designed for contractor blogs, /r/fencing or /r/HomeImprovement mods, ranch / property forums, fence-supplier sites, and homestead blogs. Required attribution is built in. Free, no signup, no analytics attached to the embed.

A fence build is one of the more tool-hungry residential projects — you're cutting, drilling, mixing, and powering through the better part of a weekend or two. Beyond the post-hole digger or auger, here's what's on every Morrison-Construction fence job:

  • Best Cordless Drills — for driving deck screws into pickets, mixing concrete with a paddle attachment, and pilot holes through pressure-treated 4×4s. The universal fence-build tool.
  • Best Miter Saws — for cutting pickets and rails to length cleanly. A 12″ sliding miter handles 2×4 rails in one pass; a 10″ handles pickets all day. The cleanest cut you'll get on a fence build.
  • Best Portable Generators — essential for long property-line fence runs where the nearest outlet is 200 ft away. A 2,000–3,000W inverter handles a drill plus a saw plus a phone charger and runs all day on 1–2 gallons of gas.
  • Best Shop Vacs — for sawdust cleanup, gravel clearing in post holes, and bagging concrete spillage. Tile / fence dust ruins a household vacuum; a dedicated shop vac handles it.

Sources & methodology

This calculator is reviewed annually for source currency. About Jake · Last reviewed April 28, 2026.

Embed this tool on your site

Free for contractor blogs, /r/fencing, /r/HomeImprovement, /r/homestead, ranch and property forums, fence-supplier sites, and personal renovation logs. Required attribution is included in the snippet. No fee, no account, no analytics attached to the embed. 

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  Fence calculator by
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  &middot; Reviewed by Jake Morrison, Licensed GC
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