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Steel Stair Stringer Bolt Hole Spacing Calculator

Calculate how many evenly-spaced bolt holes are needed along a steel stair stringer's length.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
16.4 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Bolt holes needed

13 holes

High confidence

With the figures above, the bolt holes needed comes to 13. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Add the equipment this sizes

This result is a specification — 13 holes — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Bolt hole count = ceil(stringer length ÷ maximum hole spacing) + 1, the standard method for laying out evenly-spaced connection points along a structural member

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why is 1 added to the ceiling of length divided by spacing?
Evenly-spaced holes need one more hole than the number of gaps between them — for example, 4 equal segments along the stringer require 5 holes: one at each end plus 3 in between.
Where does the maximum hole spacing come from?
It should come from your connection design — bolt shear/bearing capacity, edge distance, and gauge requirements — or your project specification. This calculator only lays out evenly-spaced holes within whatever maximum spacing you enter.
Does this check bolt capacity or edge distance requirements?
No — this only computes hole count from stringer length and maximum spacing. Connection capacity, edge distance, and gauge requirements must be checked separately as part of the connection design.