Anchor Bolt Calculator
Calculate anchor bolt quantity and spacing for sill plates, mudsills, and holdowns. Determine bolt diameter and embedment depth.
๐ฉ Anchor Bolt Calculator
Results
Bolts per Wall8
Total Anchor Bolts32 bolts
Min. Embedment7 in
Nut & Washer Sets32 sets
๐ก How to Calculate Anchor Bolt Requirements
Anchor bolts (J-bolts or L-bolts) secure the wood sill plate to the concrete foundation. IRC code requires a minimum 1/2-inch diameter bolt embedded at least 7 inches into concrete, spaced no more than 6 feet apart, with a bolt within 12 inches of each end of each sill plate piece.
In high-wind and seismic zones, spacing may be reduced to 4 feet or 32 inches. Holdown brackets at shear wall ends require additional anchor bolts โ typically 5/8-inch or 3/4-inch diameter with deeper embedment. Always check your local building code for specific requirements.
A 40 ft wall at 6 ft spacing: 40 / 6 + 1 = 8 bolts per wall. Four walls = 32 anchor bolts total. With 1/2-inch bolts, minimum 7-inch embedment into concrete.