Bolt Circle With Even Number of Holes Within Circle Measurement and Conversion Calculator

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For More equations and illustrative graphics see:
Measuring Large Bolt Circle Equations and Review

Even Number of Holes Within Circle

Even Number of Holes Within Circle: To measure or determine the unknown distance x over opposite pins (largest gage pins that can fit into holes) within a bolt circle of holes (n or number of bolts holes must be even and greater than 4), as shown left in Illustration A, use the equation:

Even Number of Holes Within Circle


y = the distance over alternate pins
d = the diameter of the holes
θ = 360°/n or angle between adjacent holes.

All units shall be consistant and given in inches or mm. Angles (theta) are given in degrees

Distance over alternate pins (y) =
Diameter of holes (d) =
Angle between adjacent holes (Theta) =
Distance over opposite pins (x) =

Automatic recalculation