Find how many newel posts a rail run needs and their spacing, with end posts included.
Newel posts anchor the handrail at the ends and at intervals along a long run. Spacing is limited by structural rigidity, commonly around six feet on center, with posts always at both ends.
Commonly no more than about 6 feet on center for rigidity, with a post at each end of the run and at every change of direction.
On long runs, yes, to keep the handrail rigid. Short runs may only need the two end posts.
At the bottom and top of each flight, and at landings where the rail changes direction.
Newel posts anchor a handrail and resist the sideways load a person puts on it, so they cannot be spaced arbitrarily. This calculator takes your run length and a maximum spacing and returns how many posts you need and how they space out evenly — always including a post at each end, where the rail starts and terminates.
As a rule of thumb, a structural newel every 6 feet or so keeps a residential rail from flexing, with posts always landing at the top, the bottom, and at any change of direction such as a landing. Decorative balusters fill the gaps between newels and follow the separate 4-inch sphere spacing rule, which the baluster spacing calculator handles.