Last updated: February 16, 2026
Perimeter Is the Number Your Fence Quote Starts With
You call a fencing contractor and the first thing they ask is “how many linear feet?” Guess wrong and you either over-order panels or run short mid-project. The most common mistake is measuring just two sides, doubling them, and calling it done —fine for a perfect rectangle, wrong for anything with an extra corner, a diagonal property line, or a gate opening. A fence length calculator takes your dimensions or coordinates, subtracts gate widths, and returns the net run of fencing you actually need to buy, plus a post count based on the spacing you choose.
The result is a material-planning number. Use it to compare contractor bids, spec a Home Depot order, or decide whether chain-link at $9/ft beats wood privacy at $18/ft for your budget. It does not account for slope, soil type, or permit requirements —those come from your contractor and your local building department.
Post Spacing Cheat Sheet
| Fence type | Typical spacing | Why |
|---|---|---|
| Wood privacy (6 ft tall) | 6–8 ft | Standard panel widths; prevents sag in wind |
| Chain-link | 10 ft | Tensioned fabric spans farther than wood |
| Wire / field fence | 12–14 ft | Lower wind load; T-posts are cheap |
| Vinyl / composite | 6–8 ft | Matches panel-kit rail lengths |
| Split rail | 8–10 ft | Decorative; no fabric to sag |
Corner posts and gate posts are always thicker (4×4 or 4″ round vs. the 4×4 or 2″ line posts). Budget those separately—they cost 2–3× more per unit but you only need a handful.
Use It in 60 Seconds
Yard: 110 ft × 55 ft rectangle, one 4-ft pedestrian gate and one 12-ft driveway gate. Wood privacy fence at 8-ft post spacing.
- Perimeter: 2(110 + 55) = 330 ft
- Gate deductions: 4 + 12 = 16 ft
- Net fence run: 330 − 16 = 314 ft
- Line posts: ⌈314 ÷ 8⌉ = 40
- Corner posts: 4 (one per corner)
- Gate posts: 4 (two per gate opening)
Cost sketch:
- Panels: 314 ft × $18/ft = $5,652
- Line posts: 40 × $22 = $880
- Corner posts: 4 × $38 = $152
- Gate posts: 4 × $38 = $152
- Gates: $125 + $350 = $475
- Subtotal: $7,311 — add 7 % waste ($512) → ~$7,823 materials before tax and labor
If the contractor quotes $12,000 installed, you know about $7.8k is material and $4.2k is labor—a 54/46 split, which is normal for a wood privacy fence. If the material line looks way off, ask which post spacing they used.
Where Fence Estimates Go Wrong
- Forgetting gate posts in the post count. Every gate opening needs two posts of its own—they’re beefier than line posts and carry hinge/latch hardware. A yard with two gates adds four extra posts. Leave them out and the material order comes up short on the sturdiest (and priciest) posts in the project.
- Using perimeter instead of net run for the material order. The perimeter of a 330-ft yard is 330 ft of boundary, but you don’t fence through the gates. If you order 330 ft of panels instead of 314, you’re buying 16 extra feet at $18/ft — $288 wasted, plus you still have to buy the gates separately.
- Ignoring slope on hilly lots. The perimeter you calculate is the horizontal distance. On a 10 % grade, the actual panel length you need is about 0.5 % longer; at 30 % grade it’s 4.5 % longer. That matters more as the run grows. The tool has a slope factor field—use it if any side of the lot is noticeably uphill.
- Skipping the waste buffer. Wood panels come in fixed lengths. Cuts at corners and angle changes produce scrap. A 5–10 % overage prevents a mid-build run to the lumber yard—and the second trip usually costs more because you’re buying a small quantity at retail instead of the bulk price.
Before You Order
How much fencing do I need for 1 acre? It depends entirely on shape. A square acre (208.7 ft per side) has a perimeter of 835 ft. A long, narrow 1-acre lot at 100 × 435.6 ft has a perimeter of 1,071 ft—28 % more fence for the same area. Always calculate from actual dimensions, not acreage.
Should I fence on the property line or inside it? Most municipalities require fences to sit 1–3 ft inside your property line. That shrinks the perimeter slightly and avoids encroachment disputes. Check your local setback rules before setting post holes.
Do I need a permit? In many US jurisdictions, fences over 6 ft need a permit, and all fences in front-yard setback zones need one regardless of height. Call your local building department before ordering materials.
Can I use this for an irregular lot? Yes. Switch to Polygon mode and enter your corner coordinates. The tool sums each segment to get total perimeter, then subtracts gates and spaces posts the same way it does for a rectangle.
Precision Notes
Rectangle perimeter is exact. Polygon perimeter is exact for the coordinates you enter; any real-world error comes from how those coordinates were measured. GPS-based boundaries should use at least four decimal places for sub-10-meter accuracy. For slopes, add the tool’s slope factor or multiply the horizontal run by √(1 + grade²) to get surface distance. Cost estimates are ballpark—get at least two contractor bids before committing.
Need the lot area too? Calculate irregular plot area from the same coordinates, or use the plot dimension tool for a quick length × width check.