100% free · Runs 100% in your browser · Posts, panels & concrete · No signup needed
Sections = perimeter / post spacing, posts = sections + 1 (one post at each end), and panels = sections. Example check: 120 ft perimeter with 8 ft spacing gives 120 / 8 = 15 sections, so 16 posts and 15 panels. Slopes, corners and gates change the real count, so measure the actual run before ordering.
Try an example: 120 ft run, 8 ft spacing, no gate
A new fence is one of the most satisfying garden jobs: one weekend of work and your outdoor space feels private, tidy and finished. It is also easy to mis-order. Buy too few posts and the fence sags; buy too few panels and you are back at the timber yard on Sunday afternoon. The Fence Calculator from FistHost works it all out before you order: posts, panels and concrete bags, from a perimeter or a simple length and width, with your choice of post spacing and an allowance for gates.
The maths is simple, but it has one trap: the number of posts is always one more than the number of sections. Every run starts with a post and ends with a post, so fifteen sections need sixteen posts, not fifteen. Forget that single post and your last panel has nothing to fix to.
The calculator builds your fence from three simple rules. First, sections = perimeter / post spacing. Divide the total length of the fence run by the distance between posts, and you get the number of sections, which is also the number of panels you need, since panels = sections. Second, posts = sections + 1, because there is one post at each end of the run as well as one between every pair of panels. Third, it estimates the concrete: each post needs a bag or two of post mix, depending on the hole size, so the calculator multiplies the post count by the bags per post.
Enter the total perimeter directly, or enter the length and width of a rectangular garden and the calculator works out the perimeter. Then pick your post spacing — 6 ft and 8 ft are the common choices, with 8 ft the usual spacing for standard panels — and deduct any gates, because a gate replaces a panel and usually needs its own posts. The result is a clear list: sections, posts, panels and concrete bags.
Measure along the line where the fence will stand, not a straight line on a map, because a fence follows the ground. For a rectangular garden, measure the length and width at ground level. For an L-shaped or irregular boundary, measure each straight run separately and add the runs together, treating each run as its own fence: a corner needs a post, so an L-shape has two runs, each with its own posts = sections + 1 rule. Mark the corners and gate positions with stakes before you measure, because moving a gate after ordering can change the panel count.
Wider spacing means fewer posts and less concrete, but the panels have to span further, so 8 ft is the practical maximum for standard timber panels. Closer spacing at 6 ft uses more posts and concrete, but the fence is stiffer and stands up better to wind. On a windy site the extra posts are worth it; on a sheltered site, 8 ft spacing is the normal choice and the calculator default.
Here is the worked check the calculator is built around. Take a fence with a 120 ft perimeter and a post spacing of 8 ft. First work out the sections: 120 / 8 = 15 sections. Panels = sections, so you need 15 panels. Posts = sections + 1, so you need 16 posts. That is the whole check: 15 sections → 16 posts, 15 panels. If you had guessed 15 posts, your last panel would have nothing to fix to at the far end.
Now add the concrete. If each post needs two bags of post mix, 16 posts need 32 bags. Change the spacing to 6 ft and the same 120 ft run becomes 20 sections, 20 panels and 21 posts, needing 42 bags. The difference is five extra posts and ten extra bags: the real cost of a stiffer fence. Try your own numbers and watch how the totals move: a small change in spacing or a single gate can move the order by several panels.
Your result lists four numbers. Sections is the number of gaps between posts. Posts is the number of uprights to buy, always one more than the sections on a single straight run. Panels is the number of fence panels, equal to the sections, minus any panels replaced by gates. Concrete bags is the estimate for setting the posts, based on the bags-per-post figure you entered. Buy the posts and panels exactly as listed, and round the concrete up.
The calculator counts materials, not fixings. You will also need panel brackets or clips, screws or nails, and gravel boards if you want the panels kept off the ground. A gravel board under each panel keeps the timber out of the damp, so add one board per panel. Post caps are cheap and keep rain out of the end grain, where rot usually starts.
Here is the honest label. Slopes, corners and gates change the real count, so measure the actual run before ordering. No calculator can see your garden: a slope means the fence steps down, and a stepped fence can need an extra post or a shorter panel at each step. Corners need posts of their own, gates need posts and hinges rather than panels, and rocky ground can force you to move a post and change the spacing of a whole run. This calculator applies the standard trade method — sections from the perimeter and spacing, posts as sections plus one, panels as sections — to the measurements you enter, and rounds up rather than down. Measure the actual run, mark your corners and gates, and treat the result as a careful buying list, not a survey.
A fence is rarely the only job in the garden, and the same free calculators can plan the rest of it. The concrete bags in your result are only an estimate, so the concrete calculator can work out the exact volume of concrete you need for post holes, a base or a slab. If you are laying a patio or a path inside the new boundary, the tile calculator estimates tiles, grout and waste from your measurements. And if your tape measure is metric and your panels are sold in feet, the unit converter switches between the two in one click.
FistHost believes useful tools should be free, fast and honest, with no sign-up and no download standing between you and the answer. The Fence Calculator runs entirely in your browser, your measurements are never sent to a server, and the result is yours to keep or share however you like. It sits alongside hundreds of other free calculators on fisthost.com, each built to solve one real problem properly, with clear maths and plain-language explanations instead of jargon.
If this calculator helped you plan a garden project, the same thinking applies to getting your ideas online. FistHost shared hosting starts from $0.99/month, and an annual plan includes a free domain, so you can launch a blog, a portfolio or a small business website for less than the cost of a coffee each month, all from fisthost.com. Fast, reliable hosting with friendly support is the simplest way to turn a plan into something real on the internet, and your first domain is on the house when you choose an annual plan.
Why do I need one more post than panels? Because posts = sections + 1: there is one post at each end of the run as well as one between every pair of panels, so a run of 15 sections needs 16 posts.
How many concrete bags per post? It depends on the hole size and the mix, but two bags of post mix per post is a common planning figure. Enter your own figure in the calculator if your holes are larger or smaller.
No reviews yet. Be the first to review this tool!
Reviews are protected by captcha and moderated before they appear.