ComponentDescriptionSymbolPulleysThree circular componentsA, B, CPulley RadiiHalf the diameter of each pulleyR₁, R₂, R₃Center DistancesDistances between pulley centersC₁₂, C₁₃, C₂₃Triangle AnglesAngles formed by center distancesα₁, α₂, α₃Belt SegmentsStraight portions of the belta’, b’, c’Belt ArcsPortions of belt wrapped around pulleyslα’, lβ’, lγ’Total Belt LengthSum of all segments and arcsL, The calculator is designed to return pulley, belt and chain information for a given set of circumstances. The measurements may be in millimetres or inches, as long as they are the same throughout. There are five main sections in the calculator, dealing with pulleys and belts (or chains and sprockets - see below ), together with speed., To calculate the total belt length (L), you need to: Determine the radii of all three pulleys (R₁, R₂, R₃). Measure the center distances between pulleys (C₁₂, C₁₃, C₂₃)..