Steel Project Index / Detailer Tools / Bolt circle · anchor layout
N bolts on a circle · X-Y coordinates · chords

Bolt circle / anchor layout

X-Y coordinates for every bolt on a circle — from bolt count, bolt circle diameter, and start angle — plus the angle between bolts and the chord length for field layout.

Formula & assumptions

X = (BCD/2)·cosθ, Y = (BCD/2)·sinθ, θ = start + i·(360/N), from center (0,0). Chord = BCD·sin(180/N). Layout aid.

Verify with project engineer, contract documents, and applicable code/specification. Estimating aid only — not a design tool, not legal advice.

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