Privacy Fence Calculator

How to use this privacy fence calculator

What this calculator does

This tool produces a planning estimate for a straight privacy-fence run. It calculates the number of sections and posts, the total post length needed to leave one-third of each post below grade, the number of horizontal rails, the picket count, and an estimated net concrete volume for the post footings. It is useful for budgeting and preparing a material list, but it does not determine structural adequacy, property boundaries, permit requirements, frost depth, gate framing, corner bracing, waste allowance, or site-specific wind loads.

When to use it

Use it while comparing fence layouts, preparing a lumber order, estimating footing concrete, or checking how a change in spacing affects material quantity. Before digging, consult the official 811 safe-digging guidance and have underground utilities located.

How to calculate

1. The calculator opens with a complete 100-foot demonstration and an immediately available Excel workbook. Replace each sample value with your project measurements.
2. Enter the total Fence length, the maximum Post spacing, and the finished Fence height.
3. Set Rails per section, then enter Picket width and Picket spacing. The results update as you type.
4. Choose Post shape and provide the post cross-section. For a round post, only the diameter is used; for a square or rectangular post, both width and thickness are used.
5. Review the material cards and calculation breakdown, then select Download Excel to save the current validated model. Reset clears the demonstration values and results; Excel export stays disabled until a complete valid set is entered again.

Input guide

Fence length is required, entered in feet as a positive decimal such as 100. Increasing it raises every material count. Post spacing is required in feet, commonly 6 to 8 for many wood privacy fences; a smaller spacing increases sections and posts. Fence height is required in feet and drives post length and burial depth. The model uses total post length = fence height ÷ 2/3, so a 6-foot fence needs a 9-foot post with 3 feet buried.

Rails per section is a required whole number, such as 3. Picket width and Picket spacing are required in inches. The picket count uses the combined repeating width, so a wider picket or larger gap reduces the count; confusing feet and inches can cause a large error. Post shape selects the buried-post volume formula. Post width / diameter is required in inches. Post thickness is required only for square or rectangular posts. Dimensions must be positive, and scientific notation or decimal commas are rejected rather than silently reinterpreted.

Output guide

Number of posts is the rounded-up section count plus one end post. Number of sections is fence length divided by post spacing, rounded up. Post length and Buried depth are dimensional estimates in feet. Number of rails equals sections multiplied by rails per section. Number of pickets is the fence length in inches divided by picket width plus spacing, rounded up. Concrete volume is the total cubic feet of the assumed post holes minus the buried post volume. A zero result is not meaningful for a complete fence; unusually high values usually indicate a unit mistake or very close post spacing.

Worked example

For the startup values – 100 feet of fence, 8-foot post spacing, 6-foot height, 3 rails per section, 5.5-inch pickets with 0.375-inch gaps, and 4-by-4-inch square posts – the calculator rounds 100 ÷ 8 up to 13 sections and adds one end post for 14 posts. It calculates 13 × 3 = 39 rails. The picket module is 5.875 inches, so 1,200 ÷ 5.875 rounds up to 205 pickets. Each post is 9 feet long with 3 feet buried. Under the stated three-times-post-size footing assumption, net concrete is 37.33 cubic feet.