Baluster Calculator

Your details

Measure from inside face of first post to inside face of last post.
ft
Include the two end posts. A straight 12-foot run typically uses 3 posts.
Width of each post (e.g. 4x4 lumber is 3.5 in actual).
in
Widest face of one baluster (e.g. 2x2 lumber is 1.5 in actual).
in
The gap you want. Building code requires no more than 4 in (10.16 cm) to block a 4-inch sphere.
in
Leave at 0 to skip the cost estimate. Enter the price of one baluster.
USD
Balusters neededCode compliant
26

Total number of balusters to purchase

Actual gap3.5
Net railing span11.13
On-center spacing5
Code compliancePass - gap (3.50 in) is within the 4-inch limit
Net railing span11.13
On-center spacing5
Actual gap3.5

26 balusters needed - spacing is code compliant.

  • You need 26 balusters to fill the railing with a 3.50 in gap between each one.
  • The on-center spacing is 5.00 in, meaning each baluster center is that far from the next.

Next stepOrder 10-15% extra to account for defects, cuts, and measurement errors.

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