How to measure a run

Measure once. Order once.

Most fencing goes wrong at the ordering stage, not the building stage — one post short, or boards bought for the wrong joist spacing.

This is the arithmetic, written out. Or skip it: the calculator on any fence panel page does the same sum from a single measurement.

Use the calculator Ask us to check it

Send it to us instead

If you would rather not do this at all, send over the length of your run, the height you want and a photo if you have one. We will come back with a list.

It is the part we are actually good at, and it costs you nothing.

Fencing

Working out a fence run

Standard panels are 6ft wide — 1.83m — and every bay needs a post, plus one extra to finish the run.

Measure the full length in metres Measure along the ground between the two end points, not diagonally, and ignore the existing fence — you are measuring the gap you need to fill.

Divide by 1.83 and round up That is your panel count. A 14m run is 7.65, so eight panels. The last bay gets cut down to fit rather than leaving a gap.

Add one post Posts go between every panel plus one at each end, so posts always equal panels plus one. Eight panels needs nine posts.

Match the gravel boards to the panels One board per bay for a level run. On a slope, use the 1ft boards to make up the fall rather than trying to step the panels.

Corners and ends are different posts An intermediate post is slotted on both sides, a corner post on two adjacent sides, an end post on one. Count these before you order — it is the single most common thing people get wrong.

Decking

Working out a deck

Decking is an area calculation, and the joist spacing decides how much framing sits underneath it.

Measure the area in metres Length times width. For an L-shape, split it into two rectangles and add them together.

Allow about eight boards per square metre That is 32mm x 125mm boards laid with a small drainage gap, which is the standard spacing.

Add 10% for cuts Every deck wastes board on cuts and the occasional reject. Ordering exactly your measured area is how you end up one board short on the last row.

Frame at 400mm centres 32mm boards span 400mm comfortably. Closer centres cost more in joists than they save; wider centres and the deck feels springy.

Treat every cut end The pressure treatment never reached the middle of the board. A cut end left bare is where rot starts.

Common sticking points

The questions that come up once the tape measure is out.

My run is not a whole number of panels. What do I do?

Round up and cut the last panel down to fit. Cutting a panel narrower is straightforward on a framed panel; leaving a gap and trying to fill it later never looks right.

The ground slopes. Does that change the count?

Not the panel count, but it changes the boards. Use the 1ft gravel boards to take up the fall so the panels stay level and step down, rather than following the slope.

Do I need a taller post than the fence height?

Yes — the post has to go into the ground as well as up. Allow roughly a third of the fence height below ground, so a 6ft fence generally wants an 8ft post.

Can I reuse my existing posts?

Sometimes, but check the base first. If the post is timber and it moves when you push it, replace it while the fence is down — it is far more work to do later.