Baluster spacing calculator
Find the minimum number of balusters and equal gaps for your opening. Download every edge and center position to mark out the layout.
Use the clear opening between the inner faces of the posts, the actual width of each baluster, and your required maximum clear gap. All three measurements use the selected unit. End gaps and internal gaps are equal. Up to 10,000 whole-width balusters and six decimal places per dimension are supported. Some width and gap combinations cannot fit. This tool lays out a straight opening; it does not determine local building-code requirements, structural strength or sloped-stair geometry. Changing units keeps the entered numbers. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Baluster spacing calculator
- Measure the clear opening between posts and the width of one baluster.
- Enter the maximum clear gap for your project and choose the shared measurement unit.
- Read the baluster count and equal gap. Download the marking positions as CSV or the complete layout as JSON.
Useful next steps
Measure the opening, not the whole rail
Measure between the inside faces of the end posts. The layout includes one equal gap at each end and equal gaps between the balusters.
Mark every position from one end
The position table gives left edges, centers and right edges measured from the left edge of the clear opening. Use one reference end to avoid accumulating rounded gaps.
Use the gap your project requires
For a 1,000 mm opening, 40 mm balusters and a maximum 100 mm gap, seven balusters leave eight 90 mm gaps. The calculator uses the gap you enter; it does not select a compliant gap for your location.