Post Spacing Calculator

Standard spacing is 6 to 8 feet. Closer spacing (6 feet) provides higher wind resistance and durability, while wider spacing (8 feet) saves on posts, concrete, and installation labor.

Posts should generally be buried at least one-third of their total height, and always below your local winter frost line to prevent shifting (usually 36" to 48" deep).

Yes. It calculates straight lines, but you can subdivide your project into individual straight walls or runs between corner terminals.

Most building codes require that a 4-inch sphere cannot pass between balusters. For standard 1.5-inch balusters, this typically means a maximum gap of 3.5 to 3.75 inches.

For solid privacy fences, 6 to 8 feet on-center is standard. Shorter spacing (6 feet) provides better wind resistance for tall privacy panels. Some high-wind areas require 4-foot spacing.

Place a post at each corner, then calculate each straight run independently from corner post to corner post. The corner post serves as the terminal point for one run and the starting point for the next.

On-center spacing measures from the center of one post to the center of the next. Clear spacing measures the open gap between post faces. Clear spacing = on-center spacing minus one post width.

At 8-foot spacing, a 100-foot fence requires approximately 14 posts (13 sections + 1 end post). At 6-foot spacing, you would need 18 posts (17 sections + 1 end post).

End posts and corner posts experience lateral forces from fence tension and should be set in larger concrete footings (12-inch diameter minimum). Line posts primarily support vertical loads and can use smaller footings.

Cable railing posts are typically spaced 4 to 6 feet apart. Closer spacing reduces cable sag between posts. Most manufacturers recommend 4-foot maximum spacing for horizontal cable runs.

Closer post spacing distributes wind load across more supports, reducing the chance of fence failure in storms. A 6-foot spacing provides roughly 33% more wind resistance than 8-foot spacing.

Yes, but stair baluster spacing is measured along the sloped rail angle, not horizontally. The 4-inch sphere rule still applies, but the spacing calculation must account for the stair pitch angle.

Deck joist hangers are installed at every joist connection point, typically 16 or 24 inches on-center. This calculator is designed for post and railing spacing, not joist spacing (use our joist calculator for that).

Drive a stakes at each end of the run, stretch a mason line between them, and use a measuring tape to mark each post location. For accuracy, measure from one end consistently rather than measuring each gap individually.

Horizontal rail fences typically use 8-foot post spacing, matching standard rail lengths. For 2x4 horizontal rails, this eliminates cutting and waste while providing adequate structural support.

A standard 4x4 fence post requires approximately 2 bags of 50-pound quick-set concrete when set in a 10-inch diameter, 36-inch deep hole. Larger 6x6 posts may need 3 bags per hole.

On sloped ground, posts are set at the same horizontal spacing but at different heights. The actual post length varies, but the spacing measurement remains horizontal, not along the slope.

Split-rail fences typically use 10-foot post spacing to match standard rail lengths. These fences are decorative and do not require the tighter spacing needed for privacy or wind resistance.

For curved fences, break the curve into short straight segments and calculate each segment separately. The shorter the segments, the smoother the curve appearance. Use 4 to 6-foot segments for gentle curves.

Pool safety fences typically use 6-foot post spacing to maintain structural rigidity. The fence must be at least 48 inches tall with no climbable features, and self-closing, self-latching gates are required by most codes.

The Post Spacing Calculator uses standard mathematical formulas validated against authoritative references. The specific formula is displayed in the calculator interface with a detailed explanation of each variable.

Each calculator includes a step-by-step worked example showing exactly how the formula is applied. You can follow these steps with pen and paper to verify any result.

The Post Spacing Calculator accepts numeric inputs including integers and decimals. Invalid inputs (letters, special characters) are rejected with clear error messages.