Free tool
Fencing calculator
Work out the panels, posts and gravel boards you need for a fence run, from the length and your panel width. Free, no sign-up.
A standard panel is 1.83m (6ft) wide.
- Posts
- 12
- Gravel boards
- 11
- Fence length
- 20 m
One post per panel plus an end post. Set each post in concrete, roughly one to two bags of postcrete each. Figures update as you type.
A fence run is panels, the posts that hold them and the gravel boards underneath, and it's easy to buy one post short. This calculator works out all three from the length of the run and your panel width. Here's how it's worked out.
How to work out how many panels you need
Panels sit end to end along the run, so the number of panels is the fence length divided by the width of one panel, rounded up.
Panels = fence length ÷ panel width.
A 20 metre run with standard 1.83m panels needs 11 panels, since 20 divided by 1.83 is just under 11. The last panel is cut down to fit, which is normal on almost every run.
How many posts
You need one more post than the number of panels, because a post stands at both ends of every panel and neighbouring panels share the post between them. So 11 panels need 12 posts. The calculator adds that end post for you, which is the one people most often forget.
Gravel boards
A gravel board is a solid board that sits under each panel, between the posts, holding the panel clear of the wet ground. It's well worth fitting: it stops the bottom of the panel rotting, and when a board does eventually go, you replace a cheap gravel board rather than the whole panel. You need one per panel span, so the count matches the panels.
Panel and post sizes
The common UK panel is 1.83m wide, which is 6 feet, in heights from 3 to 6 feet. If your panels are a different width, set it in the calculator and the panel and post counts adjust. Posts need to be long enough to bury in the ground as well as carry the panel, so a 6 foot fence usually wants a post around 2.4m to allow for the depth below ground.
Setting posts in concrete
A fence is only as good as its posts, and posts want setting in concrete. As a rule, bury about a quarter to a third of the post, so roughly 600mm for a 6 foot fence, and concrete it in. That's usually one to two bags of postcrete or a fast-set mix per post. Work out the exact concrete with our concrete calculator, using the post-holes option.
From materials to a priced job
Panels, posts and boards are the materials; the labour is in the digging, the setting and the lining up. Price the whole job with how to quote a landscaping job fast, and drop the materials into a clean, itemised quote with the quote generator.
This tool is for general estimating and gives approximate quantities. Panel widths and ground conditions vary, so check your own measurements, and order a spare post or fixings rather than exactly to the calculation.
How many fence panels do I need?
Divide the length of the fence by the width of one panel, and round up. A 20 metre run with standard 1.83m panels needs 11 panels. This calculator works it out, along with the posts and gravel boards.
How many fence posts do I need?
One more than the number of panels, because a post sits at each end of every panel, and adjacent panels share a post. So 11 panels need 12 posts. The calculator adds the extra end post for you.
What is a standard fence panel size?
The common UK panel is 1.83m wide, which is 6 feet, in heights from 3 to 6 feet. If your panels are a different width, put it in and the calculator adjusts the number of panels and posts.
Do I need gravel boards?
They're well worth it. A gravel board sits under each panel and keeps the timber off the wet ground, which stops the panel rotting from the bottom and makes it easy to replace. The calculator counts one per panel span.
How deep should fence posts go, and how much concrete?
As a rule, bury about a quarter to a third of the post, so roughly 600mm for a 6 foot fence, and set it in concrete. That's usually one to two bags of postcrete or a similar mix per post. Work out the concrete with our concrete calculator.
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