Fence Post Calculator
Buy Fence Post at Home Depot →How this calculator works
This calculator treats your fenced area as a rectangle: it computes the perimeter from the two side lengths you enter, divides by your post spacing, and adds one post to close the loop. The result is always rounded down to a whole number of spacing intervals before adding that final post, since you can’t have a fraction of a post.
Formula: Perimeter = 2 × (Length + Width). Posts = floor(Perimeter ÷ Spacing) + 1.
Worked example
A fenced yard 40 ft × 30 ft, with posts spaced 8 ft apart:
- Perimeter: 2 × (40 + 30) = 140 ft
- Posts: floor(140 ÷ 8) + 1 = floor(17.5) + 1 = 18 posts
- At $8/post, that’s $144.00.
Coverage reference
| Perimeter | Posts needed (8 ft spacing) |
|---|---|
| 100 ft | 13 posts |
| 140 ft | 18 posts |
| 200 ft | 26 posts |
How to measure your fence line
This calculator is built for a rectangular, fully enclosed run (a fenced yard with four sides) — measure the two distinct side lengths of the rectangle. A single straight fence line (not enclosing an area) uses a simpler formula instead: posts = floor(run length ÷ spacing) + 1.
Frequently asked questions
How many fence posts do I need?
Posts = the fence perimeter divided by your post spacing, plus one extra post to close the loop. Enter the two sides of your fenced area and your chosen post spacing, and this calculator gives you the exact post count.
What's a typical post spacing?
8 feet is standard for most wood and vinyl fence panels. Chain link and some prefabricated panel systems use different spacings — check your panel or fence-kit specifications and adjust the spacing field to match.
Why is there a +1 in the formula?
A straight or rectangular fence run needs one more post than the number of sections — for example, 4 panels in a row need 5 posts (one at each end and each junction), not 4.
Does this account for corner or gate posts separately?
No — this gives you the baseline post count for the perimeter. Corner posts and gate posts are usually included in that count, but gates may need a heavier-duty post than standard line posts; check with your supplier.
Estimates only. Verify quantities with your supplier before purchasing.