Fence Calculator

A fence material calculator answers one question before you spend a dollar: how much fence do I need? This tool converts a total run length, a height, a post spacing, and a gate count into the exact number of posts, rails, pickets, and concrete bags a wood, vinyl, or chain link fence requires. It works the same way for a straight backyard run or a full fence perimeter calculator job around a rectangular lot — the how to measure for a fence guide covers taking that measurement across corners, slopes, and gates before you let the math below do the rest.

For material-specific detail, use the picket fence calculator, wood fence calculator, chain link fence calculator, or vinyl fence calculator — or compare all four in the fence materials compared guide if you haven't settled on one yet. The full lineup of tools lives on the material calculators page, and every one of them uses the same formulas shown here.

This calculator handles a straight run out of the box, but the same math extends to a full property perimeter. For an enclosed rectangle, add up all four sides into one total length, then subtract gate widths before running the formula — the last post on an enclosed loop doubles as the first, so an enclosed layout needs one fewer post than the same total length run as a straight line. Fencing multiple separate runs, such as a front yard and a backyard treated independently, means running each run through the calculator on its own and adding the results together, since gate and corner counts don't carry over between disconnected runs.

How the Fence Calculator Works

Five steps turn a tape-measure number into a complete materials list, whether you're fencing a 50-foot side yard or a 300-foot property line.

1. Measure the total run in linear feet, subtracting the width of any gate openings — gate width doesn't count toward post spacing.
2. Divide by your post spacing (commonly 8 feet for wood, 10 feet for chain link) and round up to get the number of sections.
3. Add one post per section, plus one for line posts (sections + 1), then add 2 posts per gate opening.
4. Multiply sections by rails per section — 2 rails for a 4-ft fence, 3 rails for 5–6 ft, 4 rails above 6 ft.
5. Divide the clear space in each section by picket width plus gap to get pickets per section, then multiply by sections and add 5% waste.

Worked example — 100 feet of 6-ft privacy fence, 8-ft post spacing, one 4-ft gate: subtract the gate first: 100 − 4 = 96 feet of fence line. That's 96 ÷ 8 = 12 sections, so line posts = 13 (sections + 1) and gate posts = 2, for 15 posts total. Rails: a 6-ft fence uses 3 rails per section, so 12 × 3 = 36 rails. Pickets: each 8-ft section has 92.5 inches of clear space (96 inches minus a 3.5-inch 4×4 post), and a 5.5-inch dog-ear picket with no gap fits 17 per section (92.5 ÷ 5.5 = 16.8, rounded up), so 12 × 17 = 204 pickets, or 215 pickets with 5% waste. Post length: a 6-ft fence needs a 2-ft bury (height ÷ 3, minimum 2 ft), so posts run 6 + 2 = 8 feet total — an 8-ft post with a 2-ft bury. Concrete: a 4×4 post in a 10-inch hole at 24 inches deep needs 2 bags of 80-lb mix, and the 6×6 gate posts in a 12-inch hole at the same depth also round to 2 bags each, so 15 posts × 2 bags = 30 bags of 80-lb concrete.

Fence Quantity Chart by Length

Posts, rails, and pickets for a 6-ft privacy fence at 8-ft post spacing, no gates, computed with the same formulas as the worked example above.

Swap the height and the rail count changes with it: a 4-ft fence needs only 2 rails per section, while anything over 6 ft needs 4. Post count and picket count don't change with height — only spacing and picket width move those numbers. The fence post calculator breaks the post math out on its own if that's the only number you need, and the fence post spacing calculator shows equal spacing for lengths that don't divide evenly.

Materials List for a Standard Wood Fence

Beyond posts, rails, and pickets, a complete order includes a few line items this calculator surfaces but doesn't itemize by brand:

• Posts: 4×4 (3.5-in actual) for line posts, 6×6 (5.5-in actual) for gate posts and any fence over 6 ft tall, cut or bought pre-cut to stock lengths of 8, 10, 12, 14, or 16 feet.
• Rails: 2×4 lumber in 8-ft or 10-ft lengths matching your post spacing, 2 to 4 per section depending on height.
• Pickets or panels: 1×6 dog-ear boards for privacy, 1×4 spaced boards for picket style, or prefab panels for vinyl and some wood systems — see the fence board calculator and fence panel calculator.
• Hardware: roughly 2 screws or nails per picket per rail it crosses, plus post caps and optional brackets.
• Concrete: 80-lb, 60-lb, or 50-lb bagged mix, sized per post by the concrete per fence post calculator.

Post Depth and Concrete

Post depth follows one rule: bury at least a third of the total post height, with a 2-ft minimum. A 6-ft fence needs a 2-ft bury, an 8-ft fence needs a 3-ft bury, and frost line in cold climates can push that deeper — check the fence post depth and frost line guide for your state before digging. Hole diameter runs about three times the post's actual width — 10 inches for a 4×4, 12 inches for a 6×6 — and each hole's volume converts directly to a bag count on the concrete calculator for fence posts. Always call 811 before you dig to have underground utility lines marked, and check the fence height rules and permits guide for typical height limits before you finalize a design.

Waste and Ordering

Add 5% to pickets and rails to cover cutting errors, warped boards, and end-of-run trims — that's the difference between 204 and 215 pickets in the worked example above. Posts and concrete don't need a waste factor since you're not cutting them to a non-standard length. Order pickets and rails in full bundle or unit quantities where your supplier sells them that way, since rounding up to the next bundle usually beats a second delivery trip for a handful of boards.

Sloped yards need one more adjustment before you order: a fence can either step down a hill in level sections with a small gap under each panel, or rack to follow the slope at an angle, and racking usually needs the same picket count with slightly longer posts at the low end of each section. Measure the grade change across your run and add extra post length on the downhill side rather than assuming every post uses the same stock length.

Next Steps

Once you know your exact post, rail, and picket count, the fence cost calculator turns those quantities into an installed price range for materials and labor in your area.