How to Lay Out a Fence Line
Order of operations
- Confirm the property line and call for utility locates (811 in the US). Both before anything else.
- Stake the corners and ends — a stake at every corner and terminus.
- Run string between stakes, pulled tight, a few inches above grade. This string is the fence; every post centre gets marked along it.
- Decide gate positions now. Gates are fixed openings and their posts are non-negotiable points; line posts divide up whatever is left.
- Mark post centres at the actual spacing, measuring cumulatively from one end.
- Dig, set, brace — then build.
Getting the line straight and square
String pulled between two stakes is straight by definition; the trick is keeping it that way while you work. Use a mason's line, pull it genuinely tight, and support it at intervals on long runs so it cannot sag or blow into a curve.
For a corner that must be square, use the 3-4-5 method: measure 3 ft along one line, 4 ft along the other, and adjust until the diagonal between those marks is exactly 5 ft. Any multiple works, and 6-8-10 is more accurate over a longer distance.
Measure cumulatively, not post to post
Mark post centres by running the tape from one end and noting each position — 0, 7.7, 15.4, 23.1 ft and so on. Do not measure 7.7 ft from the last mark each time. Post-to-post measuring accumulates error, and by the far end you can be a foot out with nowhere to hide it.
The fence calculator gives the actual spacing after dividing the run evenly, which is the figure to step off. Write the cumulative marks on a scrap of paper before you start.
Gates come first
A gate opening is a fixed width: the gate leaf plus hinge and latch clearance, typically about 3/4 in total for a wooden gate. Set the two gate posts at exactly that spacing, then divide the remaining runs into equal bays.
- Put gates where the path actually goes, not where the bay arithmetic is convenient.
- Consider which way the gate swings and whether it clears the slope.
- A double gate for a wide opening sags less than one very wide leaf.
- Gate posts take the whole load — go one size up and one hole depth deeper.
Sloping ground: step or rake
| Approach | How it looks | Best for |
|---|---|---|
| Stepped — panels stay level, each bay drops | Level top lines with steps between; triangular gaps at the bottom | Pre-made panels, formal fences, moderate slopes |
| Raked — rails follow the grade | Continuous line parallel to the ground, no gaps | Site-built picket and board fences, gentle slopes, keeping pets in |
Raking means every picket is cut to a slightly different length and the rails meet the posts at an angle. Stepping is simpler to build but leaves a gap under each panel, which matters if the fence is meant to contain a dog.
Set posts before you build anything
Dig all the holes, set and brace all the posts, and let the concrete cure before hanging a single rail. It is tempting to work bay by bay, but a post pushed out of plumb while nailing rails to green concrete stays out of plumb permanently. Check plumb on two adjacent faces of every post, and check the tops against the string line as you go.
Run the fence calculator once the line is staked and measured: it converts run length, spacing and gate widths into posts, rails, pickets and the concrete bags for every hole.
Enter the run length and post spacing to get posts, sections, rails and pickets — plus the concrete needed to set every post, which is usually the item people underestimate.
Frequently asked questions
How do I make sure a fence line is straight?
Stake the ends and corners, then run a tightly pulled mason line between them a few inches above grade and mark every post centre along that string. Support the line at intervals on long runs so it cannot sag or bow.
Should I measure post spacing from the last post?
No. Measure cumulatively from one end — 0, 7.7, 15.4 feet and so on. Measuring each gap from the previous post accumulates small errors until the last bay is visibly wrong.
How do I lay out a fence on a slope?
Either step the panels, keeping each bay level and dropping between bays, or rake the fence so the rails follow the grade. Stepping is easier and suits pre-made panels; raking leaves no gaps at the bottom, which matters for containing animals.
How much clearance does a gate need?
About three quarters of an inch in total for a wooden gate — enough for the hinge on one side and the latch on the other. Set the gate posts to the leaf width plus that clearance, and place the gate before dividing the remaining bays.