A fence material calculator takes the guesswork out of buying for a fencing project. Instead of standing in the timber yard doing rough sums on the back of an envelope, you enter your fence length, panel size and style, and get an instant materials list: how many panels or pickets you need, how many posts, how much concrete for the footings, and how many rails or gravel boards to finish the job.
This matters because fencing is one of those jobs where under-buying costs you a second delivery (and a wasted Saturday), while over-buying leaves you with stacks of timber you’ll never use. Whether you’re replacing a storm-damaged boundary fence or fencing a whole new garden, having a solid materials estimate before you start keeps the budget in check and the project on schedule. It’s built for DIYers tackling their first fence as well as experienced hands pricing up a job quickly.
If you’re also thinking about the budget side of the project, our guide on building a garden fence: materials and cost walks through typical prices for timber, posts and fixings so you can turn your materials list into a full cost estimate.
How to Use the Fence Material Calculator
- Enter the total fence length. Measure along the line where the fence will run, in feet or metres. For an L-shaped or U-shaped run, measure each straight section and add them together — corner posts handle the joins.
- Choose your fence style. Select panel fencing (pre-made 6×6 ft or 1.83×1.83 m panels), close-board (featheredge) fencing built on site, or picket fencing. The calculator adjusts the materials list to match.
- Set your fence height. Common choices are 4 ft, 5 ft or 6 ft. Taller fences need longer posts and deeper footings — the calculator adds this automatically.
- Pick post spacing. For panels, posts typically sit at each panel joint (one post per panel plus one at the end). For close-board and picket, posts go every 6–8 ft. The calculator defaults to the standard spacing for your style, but you can adjust it.
- Review your materials list. You’ll see the number of panels or pickets, posts, rails, gravel boards, bags of post-mix concrete, and fixings. Adjust any figure and re-check if you change the design.
- Add a wastage allowance. Timber varies and cuts go wrong — add 5–10% to your order so you don’t run short. The calculator includes a wastage toggle for this.
How the Calculation Works
The calculator works from simple length arithmetic. First it divides your total fence length by the width of one panel (or the post spacing for built-on-site fences) and rounds up to the nearest whole number — you can’t buy half a panel. For panel fencing, posts equal the number of panels plus one (the final end post). For a close-board fence, it multiplies the length by the number of boards per metre (typically 5–6 featheredge boards per metre for a 150 mm overlap) to get the board count, then calculates posts from your spacing, arris rails (usually 3 per 6 ft bay for a 6 ft fence), and capping or counter rails if selected.
Concrete is estimated per post: a standard post hole is roughly 1 ft (300 mm) square and 2 ft (600 mm) deep for a 6 ft fence, which takes about one 20 kg bag of post-mix per post — a bit more in loose or sandy soil. The calculator multiplies bags-per-post by your post count.
Worked example: A 60 ft garden boundary using 6×6 ft panels. 60 ÷ 6 = 10 panels, plus one end post = 11 posts. Concrete: 11 posts × 1 bag = 11 bags of post-mix. Add one gravel board per panel (10) and a 10% wastage allowance on panels → order 11 panels to be safe. With a material price of, say, £30 per panel and £8 per post, that’s roughly 10 × £30 + 11 × £8 + concrete and fixings ≈ £500–550 for materials.
Tips for Accurate Results
- Measure twice, on the ground. Walk the fence line with a tape measure rather than estimating from a plan. Slopes, trees and existing structures all change the real length.
- Subtract gates and existing sections. If part of the run already has a fence you’re keeping, or you’re adding a gate, measure those sections separately and exclude them from the length.
- Account for ground slope. On a slope, panels step down and each bay may need slightly longer posts. Add an extra 6 inches of post length if the ground falls away across the run.
- Check local rules on height. In the UK, fences over 6 ft 6 in (2 m) usually need planning permission; in the US, check your HOA and local codes. A taller fence changes posts, rails and concrete quantities.
- Buy posts slightly longer than you think. For a 6 ft fence, 8 ft posts are standard — 2 ft goes in the ground. Skimping on post depth is the number one cause of leaning fences.
- Order everything from one supplier. Timber varies in colour and quality between batches, so getting panels, posts and rails from one yard gives a more consistent finish.
Frequently Asked Questions
How many fence posts do I need?
For panel fencing, you need one post per panel plus one extra for the end — so 10 panels need 11 posts. For close-board or picket fences, divide your total length by your post spacing (typically 6–8 ft) and round up, then add one. The calculator above does this for you.
How deep should fence posts be buried?
A good rule is one-third of the post in the ground, with a minimum of 2 ft (600 mm) for a 6 ft fence. In soft or sandy soil, go deeper — up to 2 ft 6 in — and use more concrete. Shallow posts lean within a year or two.
How much concrete do I need per fence post?
For a typical 1 ft × 1 ft × 2 ft post hole, one 20 kg bag of post-mix per post is a reliable estimate. In loose soil where the hole ends up wider, allow 1.5 bags per post. Post-mix sets fast (often in 10 minutes), which speeds up the job.
Should I use gravel boards?
Gravel boards sit at the base of the fence and keep the panels off the soil, which can double the life of the timber. They’re cheap relative to the cost of replacing rotten panels early, so for timber fences they’re almost always worth it.
Can I build a fence on a slope?
Yes — most panel fences are stepped down a slope, with each bay sitting level and dropping at each post. You’ll need longer posts where the ground falls away. On steeper slopes, close-board fencing built on site follows the ground more gracefully than rigid panels.
If you plan to paint or stain the new fence, check how much paint do I need — the same coverage maths works for fence stain, and getting the quantity right first time avoids mismatched colour batches.