Bolt Circle (BCD) Coordinate Calculator
SI
Imp
Imperial
Inputs
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Bolt circle diameter
(BCD)
Diameter of the circle the hole centers lie on (the radius is half this).
mm
Number of holes
(N)
How many holes are equally spaced around the bolt circle.
Start angle
(θ₀)
Angle of the first hole, CCW from the +X axis.
°
Center X
(cx)
X coordinate of the bolt-circle center.
mm
Center Y
(cy)
Y coordinate of the bolt-circle center.
mm
Results
Default result
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Angular spacing
(Δθ)
60
°
360° ÷ holes
Also computed
Chord between holes
(c)
50
mm
Method notes
6 notes
Hole 0: X = 50.000, Y = 0.000 (mm)
Hole 1: X = 25.000, Y = 43.301 (mm)
Hole 2: X = -25.000, Y = 43.301 (mm)
Hole 3: X = -50.000, Y = 0.000 (mm)
Hole 4: X = -25.000, Y = -43.301 (mm)
Hole 5: X = 25.000, Y = -43.301 (mm)
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