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Why even fence post spacing matters
A fence with even post spacing looks right the moment you see it. A fence with one short bay at the end looks like a mistake, even if it is strong. The eye notices uneven gaps fast, especially on a long straight run along a garden or a driveway. Even spacing also spreads wind load evenly, so no single bay carries much more than its neighbours. That is why builders plan the spacing before they dig the first hole, not after the last post is in the ground.
This calculator does that planning for you. Enter the total length of the run and the widest spacing you are willing to accept, and it divides the run into equal bays. The number of posts is always one more than the number of bays, because every bay needs a post at each end. If your run is 100 feet and you allow 8 feet between posts, you get 13 bays of about 7.69 feet and 14 posts. The spacing is slightly tighter than your maximum, which is exactly what you want.
How to use the calculator
- Measure the total run from the centre of the first post position to the centre of the last one.
- Enter the widest spacing your fence design allows. Eight feet is common for wood fences; vinyl and metal panels often fix their own spacing.
- Read the even spacing and the post count, then mark the centres on the ground before you dig.
A worked example
Suppose a back garden run measures 60 feet and the panels you bought are made for posts up to 8 feet apart. Dividing 60 by 8 gives 7.5, so you round up to 8 bays. Sixty divided by 8 is exactly 7.5 feet per bay, and you need 9 posts. If you had placed posts every 8 feet without planning, the last bay would have been only 4 feet wide, and the fence would have looked patched together. Planning first costs two minutes and saves an afternoon of rework.
Corner posts and gate posts deserve special care. A corner post carries load from two directions, so builders often set it deeper and in more concrete than a line post. A gate post carries the weight of the gate every time it swings, so it should be the strongest post on the run. Count them in your total, but treat them as separate jobs when you dig and set them.
Tips for a straight, strong fence
- Run a string line between the two end posts before you mark the middle posts. A string line is the cheapest way to keep a fence straight.
- Measure post centres, not post edges. A 4 inch post measured from the wrong edge throws every bay off by inches.
- Dig below the frost line in cold climates. A post that heaves in winter will lift the whole bay with it.
- Keep the bottom of wood posts out of standing water. Gravel at the base of the hole drains better than soil packed tight.
Common mistakes
The most common mistake is trusting the panel length instead of the run length. Panels are sold as 8 foot panels, but the real distance between post centres is often a little less once the panel sits in its brackets. Measure the run, divide it evenly, and let the panels follow the posts, not the other way round. Another common mistake is spacing posts by eye. Two bays that look even from one end can be visibly uneven from the other, and the eye catches it from the street.
Remember that this tool is a planning estimator, not a building code. Fence height rules, boundary rules and pool fence rules differ by town, and they govern what you may build. Check them before you dig, and call your local utility marking service so you do not hit a buried line. Even spacing is the easy part of a fence; the rules and the digging are the parts that need care.