Handrail & Baluster Calculator
Calculate handrail length along the slope, number of balusters, baluster cut lengths, and newel post locations for stair railings. Free calculator with SVG diagram.
Newel Post Locations
Newel posts placed at bottom, top, and every 8 ft of handrail length
Baluster Schedule
| # | Distance Along Slope | Cut Length |
|---|---|---|
| 1 | 0.0" | 36.00" |
| 2 | 5.4" | 36.00" |
| 3 | 10.8" | 36.00" |
| 4 | 16.1" | 36.00" |
| 5 | 21.5" | 36.00" |
| 6 | 26.9" | 36.00" |
| 7 | 32.3" | 36.00" |
| 8 | 37.7" | 36.00" |
| 9 | 43.1" | 36.00" |
| 10 | 48.4" | 36.00" |
| 11 | 53.8" | 36.00" |
| 12 | 59.2" | 36.00" |
| 13 | 64.6" | 36.00" |
| 14 | 70.0" | 36.00" |
| 15 | 75.3" | 36.00" |
| 16 | 80.7" | 36.00" |
| 17 | 86.1" | 36.00" |
| 18 | 91.5" | 36.00" |
| 19 | 96.9" | 36.00" |
| 20 | 102.2" | 36.00" |
| ...and 11 more at 36" each | ||
How It Works
Enter the total run and total rise of your staircase, then set the baluster spacing (max 4" per IRC code) and baluster width. The calculator computes the handrail length along the slope and the exact number of balusters needed.
Handrail length is the hypotenuse of the rise and run triangle — longer than the horizontal run because it follows the slope of the stairs.
Baluster count is determined by dividing the handrail length by the on-center spacing (baluster width + clear space) and adding 1 for the end.
Newel posts are placed at the top, bottom, and every 8 feet of handrail length. They are structural members that anchor the railing system.
Cut lengths for plumb balusters on a sloped rail are all the same (36") because the tread line and rail line are parallel.
Frequently Asked Questions
What is the maximum baluster spacing per building code?
The IRC requires that balusters (spindles) be spaced so that a 4-inch sphere cannot pass through. With standard 1.5"-wide balusters, this means 4" of clear space between each baluster, or 5.5" on-center spacing.
How tall should a stair handrail be?
The IRC requires stair handrails to be between 34 and 38 inches high, measured vertically from the stair nosing to the top of the rail. Most builders default to 36 inches for a comfortable grip height.
Where do newel posts go on stairs?
Newel posts are required at the top and bottom of every stair flight, and at any turn or landing. For long straight runs, structural newel posts should be placed every 8 feet of handrail length to maintain rigidity.
Are stair baluster cut lengths all the same?
For plumb-cut balusters on a stair railing, each baluster is the same length (typically 36") because both the tread line and the handrail are parallel — they have the same slope. The balusters are cut square at both ends and installed plumb (vertical).