Free Anchor Bolt Spacing Calculator
Calculate the number of anchor bolts and their spacing for a sill plate on a foundation wall.
ft
ft
in
Anchor Bolts Needed
10
Actual Spacing0.00 ft
Anchor Bolts Needed vs Wall Length
Anchor Bolt Layout
The IRC requires anchor bolts no more than 6 feet apart, with one bolt within 12 inches of each end of the sill plate and each side of openings. Seismic zones may require closer spacing (4 ft) or larger bolts.
Interior bolts = ceil(Interior Length / Spacing) + 1 Total = Interior + 2 end bolts
Example Calculation
40 ft wall, 6 ft max spacing, 12 in from ends.
- 01Interior length = 40 - 2 = 38 ft
- 02Interior sections = ceil(38/6) = 7
- 03Interior bolts = 7 + 1 = 8
- 04Total = 8 + 2 end bolts = 10 anchor bolts
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