Fence Calculator

How to use the fence calculator

Measure each straight solid fence run separately. Start a new run at an end, a corner or a gate opening. Enter gate openings separately, then choose the U.S. or Metric measurement system and the material mode that matches the product you are planning to use.

Use actual product dimensions and the spacing that applies to your chosen fence design. Prices are optional and come only from values you enter.

The calculator estimates quantities from the dimensions and assumptions you enter. It does not choose structural spacing, post depth, permits or setbacks for your project.

How fence posts and sections are calculated

Each straight run is rounded on its own. For individual boards or post-and-rail, sections for a run = ceiling(run length ÷ selected maximum spacing). For prebuilt panels, the selected actual installed panel width replaces the spacing and determines each run's panel bays.

For an open layout, posts = total sections + 1 + gate openings. For a closed perimeter, posts = total sections + gate openings. Each gate opening has two structural edges in this topology model, while the additional end post applies only to an open path.

Runs are rounded separately because a corner or gate creates a real layout point. Combining every side into one perimeter first can hide a section that is needed on one particular run. This model assumes one contiguous fence path; estimate fully disconnected lines separately.

How rails, pickets and panels are estimated

Rail quantity is the calculated number of bays multiplied by your rails-per-section input. It assumes one rail piece spans one bay. If an optional purchased rail length is shorter than a calculated bay, the result shows a warning; it does not create an optimized stock-cut list.

For individual boards, the base picket count is calculated on each run from run length ÷ (actual board width + clear gap), then rounded up per run. Prebuilt panel counts use the actual installed panel or bay width you enter. Nominal product dimensions may differ from installed dimensions, so check brackets and current product details with the supplier or manufacturer.

The material allowance starts at 0% and is optional. If entered, it applies only to whole rails, pickets or panels. It does not change the structural post, gate or concrete quantities.

How post-hole concrete is estimated

The tool uses a cylindrical hole, subtracts the volume displaced by the embedded part of each post, multiplies by the structural post count and divides the resulting volume (plus any concrete allowance) by the yield you enter for one bag. The yield is a volume from the product label; bag weight alone does not tell you its finished volume.

Hole size, depth, post dimensions and concrete yield are project inputs, not construction recommendations. If gate or corner posts use different hole dimensions, calculate those separately. For the concrete method and another set of inputs, see the Concrete Calculator and concrete for fence post holes guide.

Worked example: a 100 ft fence line with one gate

Illustration only. Enter an open layout with two 48 ft solid runs, one 4 ft gate opening, 8 ft maximum post spacing, three rails per section, 5.5 in actual boards, 0.25 in gaps and a 5% material allowance. These values demonstrate the arithmetic; they are not construction recommendations.

• Run 1: ceil(48 ÷ 8) = 6 sections.
• Run 2: ceil(48 ÷ 8) = 6 sections; total = 12 sections.
• Open layout posts: 12 + 1 + 1 = 14 structural posts.
• Total line span: 48 + 4 + 48 = 100 ft, including the gate opening.
• Rails: 12 × 3 = 36 before allowance; ceil(36 × 1.05) = 38 rails.
• Picket module: 5.5 + 0.25 = 5.75 in. Each 48 ft run is 576 in; ceil(576 ÷ 5.75) = 101 boards per run. Base = 202 pickets; with the illustrative 5% allowance, ceil(202 × 1.05) = 213.

The 8 ft spacing and 5% allowance in this example are sample inputs only, not universal construction recommendations.

Optional concrete arithmetic for the same 14 posts

For 14 posts, suppose the entered assumptions are 10 in round holes, 30 in hole depth, an actual 3.5 × 3.5 in square post, 30 in embedded depth, a 0.60 cu ft bag yield and 0% concrete allowance. The net geometric volume is approximately 16.11 cu ft; 16.11 ÷ 0.60 rounds up to 27 bags. These hypothetical dimensions do not say what hole or post size is right for another project.

What this estimate does not include

The fence material estimator does not perform structural or wind engineering, determine post spacing, account for soil or frost depth, engineer gate posts, establish a property boundary, determine setbacks or permits, interpret HOA requirements, model stepped or racked slopes, optimize board-on-board or shadowbox overlap, count chain-link mesh or hardware, specify fasteners, select a concrete mix, or estimate labor productivity. Supplier packaging is included only when represented by the inputs you provide.

Before buying materials

Recheck the measured line, run breaks, gate clear widths, actual board or installed panel dimensions, brackets, rail stock and product installation instructions. Confirm supplier quantities and any local requirements before ordering.

Before digging in the United States, use the official 811 Call Before You Dig service to locate underground utilities. Use the equivalent local utility-locating service outside the U.S. Notification rules and timing vary by location.

This calculator does not establish legal property boundaries, determine setbacks, provide permit advice or perform structural/wind engineering. Check local rules and product instructions separately.

Fence calculator questions

How many fence posts do I need?

It depends on the length and number of straight runs, the spacing or installed panel width you enter, the gates and whether the path is open or closed. Each run is rounded separately before the post formula is applied.

Should gate width be included in fence length?

Leave clear gate openings out of the solid run lengths and enter each separately. The calculator adds their widths to the total project span and adds a gate-opening post allowance to the layout count.

Can I use the fence calculator in metres?

Yes. Select Metric (m/mm). Switching systems converts the dimensions already entered so they retain the same physical size.

Does the calculator estimate fence cost?

Only from the prices, labor rate and other cost you enter. It does not fetch supplier prices or estimate current local or national pricing. Currency changes formatting only.

Related tools

• How to measure fence runs, gates and corners before entering a layout.
• For a project-specific coating area, use the Paint Calculator.
• Browse Roofing & Construction calculators for related material estimates.

Privacy: Calculations run in your browser. Entered fence measurements and prices are not sent to a calculation server or saved in an account.