Measure the run in metres. The tally is the panels, posts, Postcrete and gravel boards for that one line.
How this tally counts
A bay is one panel width. The box starts at 1.83 m, the usual UK panel. Change it if yours are a different width.
Full bays are whole panels. If the last bay comes up short, the tally calls it a cut panel. You still buy a whole panel and saw it down. A remainder of 20 mm or less is taken up in the joints, and it is not a cut. If the tape is up to 20 mm short of another full panel, that panel is counted and there is nothing to cut. Either way, the tally shows the millimetres.
A gate is taken out of the run before the panels are counted. It still counts as a bay for the posts. It does not get a gravel board.
Posts are one more than the bays, unless an end fixes to a wall. Postcrete follows the post size and the hole on the Postcrete page, in 20 kg bags.