How Do I Calculate Fence Materials for an Odd Shaped Yard?

Break the boundary into straight runs

To calculate fence materials for an odd shaped yard, do not measure the perimeter as one loop. Walk the property line and split it into straight runs, marking every corner, gate opening and direction change. Measure each run in feet from corner to corner, then add the runs together to get total linear feet. The calculator works run by run rather than from one total, because an angled or stepped boundary wastes material at each turn. A run that ends mid-panel still needs a full panel and a post, and that rounding happens per run, not once at the end. Write each measurement down as you go, including the gate width, so nothing is reconstructed from memory later.

A typical US lot may have four or five runs: a front line, two side lines, a rear line and a short return beside a driveway. Measure along the line where the posts will sit, not along the house wall or a planting bed. If a run is not straight, split it again at the bend. Two shorter runs give a more honest count than one long average, because each bend adds a post and usually a cut panel.

Convert each run into posts and panels

The default bay is 8.00 ft, so a run of 37 ft needs five bays: four full 8 ft bays plus a 5 ft closing bay. That is six posts, one at each end of the run. The calculator divides run length by 8.00 ft, rounds up to whole bays, then adds one post per run. Panels are counted as whole units, so the 5 ft remainder is ordered as a full 8 ft panel and trimmed on site. Rails follow at two per bay, so five bays need ten rails.

Worked example: a rear run of 42 ft gives 42 divided by 8.00 equals 5.25, rounded up to 6 bays, 7 posts and 12 rails. A side run of 29 ft gives 3.63, rounded to 4 bays, 5 posts and 8 rails. Add the runs and the totals accumulate run by run. If you are building with pickets instead of panels, the same bay count applies, and picket quantity comes from 89 mm pickets with a 13 mm gap across each bay.

Count posts, concrete and gates

Posts are the item most often under-ordered in an irregular yard, because every corner and every gate jamb takes one. Count one post at the start of each run and one at the end, then check shared corners so a corner post is not counted twice. Gate openings need a post on each side, heavier than a line post. Give the calculator the gate width and it returns the gate count separately from the panels.

Concrete uses a 254 mm diameter hole by 762 mm deep, about 0.039 m³ per hole. An 80 lb bag yields about 0.017 m³, so each hole needs roughly three bags. For the 42 ft rear run with 7 posts, that is 21 bags before allowing for wider corner holes. Confirm bag yield on the supplier's printed label, since mixes vary. For permit rules, setback limits and height caps, check with your local building department before ordering.

Build the order list and check it

Total the runs, then list posts, panels, rails, concrete bags and gates as separate lines. Add one spare panel and a few spare pickets for trimming and breakage. Reconcile the list against the measured runs: every run should show its bay count, its post count and its rail count, and the sum of run posts minus shared corners should match the post line. If the numbers disagree, the error is almost always a double-counted corner or a gate opening measured but not subtracted from the panel run.

Prices vary by supplier, species and height, so enter your own unit costs rather than relying on a default. The fence calculator returns a material cost from those inputs, which is useful for comparing quotes. Delivery times and stock levels are set by the yard, so confirm both before you fix a build date. Keep the run-by-run sheet with the quote; it makes shortfalls and returns far easier to argue.

Where odd shapes change the numbers

Angled boundaries, curved beds and stepped slopes all add posts relative to a straight rectangle of the same perimeter. A curve measured as one run will under-count, because the calculator rounds bays, not curvature. Split a curve into chords of about 8 ft and treat each as a run. Sloped ground may need stepped panels and longer posts; confirm post length with your supplier rather than assuming the standard height works.

Default height is 6.00 ft, and any change to height affects panel and picket quantities but not post spacing. If local rules cap height, check before you buy taller panels. For shared boundary lines, confirm the ownership and responsibility with your neighbor and the local authority before measuring from their side.

A full worked total

Take a yard with four runs: 42 ft rear, 29 ft left side, 31 ft right side and 24 ft front, with a 4 ft gate in the front run. Rear: 6 bays, 7 posts, 12 rails. Left: 4 bays, 5 posts, 8 rails. Right: 31 divided by 8.00 equals 3.88, so 4 bays, 5 posts, 8 rails. Front: subtract the 4 ft gate, leaving 20 ft, which is 2.5 bays, rounded to 3 bays, 4 posts and 6 rails, plus one gate.

Totals before corner adjustment: 17 bays, 21 posts, 34 rails, 1 gate. Four shared corners mean four posts counted twice, so order 17 posts. Concrete at three bags per hole is 51 bags, plus a few spares. Add one spare panel. That is the order list, and every line traces back to a measured run.

Frequently asked questions

The FAQ entries below cover the points that most often trip up a first measurement.

Frequently asked questions