How far apart should fence posts be?
Six to eight feet on centre, and the run divided evenly rather than one short panel at the end. Post counts for every fence length.
A 100' run at no more than 8' between posts takes 14 posts, landing 7 ft 8 5/16 in apart.
13 equal spans rather than 12 full ones and a short remainder — the eye reads an uneven last panel from across the garden.
How that is worked out
- Divide the run by the widest spacing the fence style allows, and round the number of spans *up*. That gives more posts, each span a little under the maximum.
- 100' ÷ 8' = 12.50, so 13 spans — and one more post than spans, because the run has two ends.
- 1200" ÷ 13 = 7 ft 8 5/16 in on centre, the same for every panel.
Posts for a straight run, spans divided evenly
| Run | At 6' max | At 8' max | Actual spacing at 8' max |
|---|---|---|---|
| 20' | 5 | 4 | 6 ft 8 in |
| 40' | 8 | 6 | 8 ft |
| 50' | 10 | 8 | 7 ft 1 11/16 in |
| 75' | 14 | 11 | 7 ft 6 in |
| 100' | 18 | 14 | 7 ft 8 5/16 in |
| 150' | 26 | 20 | 7 ft 10 3/4 in |
| 200' | 35 | 26 | 8 ft |
Worth knowing
- 8' is the usual maximum because rails come in 8' lengths and a longer span sags. 6' is better for a solid privacy fence, which catches wind like a sail and puts real load on every post.
- Pre-made panels set the spacing for you, and they are unforgiving: the posts have to land exactly at the panel width or the panel does not fit. Build-in-place fences are the ones where dividing the run evenly is your choice to make.
- Set the end and corner posts first, run a string between them, and lay out from the string. Measuring post to post accumulates error and the last panel absorbs all of it.
- Gate posts are a different problem. A gate hangs off one post as a cantilever and that post wants to be bigger, deeper and set in more concrete than the line posts either side of it.
Work out your own numbers
- Fence post spacing
Post count and the actual on-centre spacing for any run and maximum span.
- Concrete footings and slabs
Cubic yards for a run of post footings or a slab, and the bags of ready-mix that buys.
- Baluster and slat spacing
Even gaps across any span, checked against the 4-inch guard rule, with tape-measure marks that don't drift.
Related questions
- How far apart should fence posts be?
- 6 to 8 feet on centre. 8' is the practical maximum because rails come that long and anything further sags; 6' is better for solid privacy fencing, which takes wind load across its whole face. Divide the run evenly rather than running full spans and leaving a short panel at the end.
- How many posts do I need for a 100 foot fence?
- 14 at a maximum 8' spacing — 13 equal spans of about 7'8" plus the post at each end. The count is always one more than the number of spans, which is the arithmetic people most often get wrong by one.
- Should fence spacing be measured on centre or between posts?
- On centre, because that is what the rails and panels are sized to. The clear gap between posts is smaller by one post width, which matters when you are fitting pre-made panels — a panel sized to the on-centre spacing will not fit between the posts.