Quick Calculators · Free to use
Baluster Spacing Calculator
Calculate baluster count and equal clear gaps from an opening, baluster width, and your maximum spacing.
Your estimate
Enter your measurements to see the estimate.
Balusters
balusters- Actual equal clear gap
- On-center spacing (when balusters are used)
Straight equal-width balusters with equal gaps at both posts. Planning geometry only: does not certify guard strength, stair openings, or code compliance. When no baluster is needed by the entered limit, on-center spacing is shown as 0 (not applicable).
Show the math for your measurements
Optional practical gap layout
How to Use This Calculator
Calculate baluster count and equal clear gaps from an opening, baluster width, and your maximum spacing.
Decimals and fractions accepted for dimensions. Unmarked values use the labeled unit; explicit feet/inches are converted. For example, 10' 6 1/4" is an explicit length; 10.6 means 10.6 of the labeled unit. Rates, prices, counts and areas use numbers only.
Inputs and where to find them
Clear opening between posts (in). Measure the clear horizontal distance between the inside faces of the posts or other boundaries. Do not use post-center spacing. The full opening is filled by the baluster widths and all the clear spaces, including a space at each end.
Actual baluster width (in). Measure the actual width that each baluster occupies along the opening. A decorative or tapered profile may need particular attention at the height being checked. All balusters in this calculation use the same entered width.
Maximum permitted clear gap (in). Enter the largest clear opening permitted by your project requirements. This is the space between faces, not the distance between baluster centers. The calculator uses your limit to find a minimum count; it does not select or certify the applicable guard requirement.
Results, example and assumptions
The quantity is the smallest whole baluster count that meets the entered clear-gap limit with equal spaces. There is a space at each end, so the gap count is one greater than the baluster count. Clear gap is measured between faces; on-center spacing is measured between adjacent baluster centers and is not applicable with fewer than two balusters. The drawing shows this equal-gap arrangement. The optional practical layout is separate: its listed gap sizes may differ, but their total closes the opening and each respects your limit. Do not repeat a rounded equal-gap reference across the opening.
Count = max(0, ceil((opening − maximum gap) ÷ (baluster width + maximum gap))). Actual clear gap = (opening − count × width) ÷ (count + 1). On-center spacing = width + gap.
Worked example: A 60 in opening, 1.5 in balusters, and a 4 in maximum gap require 11 balusters. The 12 clear gaps are 3.625 in; centers are 5.125 in apart.
Use equal-width balusters between straight, parallel boundaries. Planning geometry only: does not certify guard strength, stair openings, or code compliance. When no baluster is needed by the entered limit, on-center spacing is shown as not applicable.