Metric bolt torque calculator and chart to show metric bolt torque values and assembly preloads permitted for the bolts. Bolt torque values are calculated by using calculation tables and tightening torque - preload formulas given in the VDI 2230 "Systematic calculation of high duty bolted joints - Joints with one cylindrical bolt" standard. Assembly preload and tightening torque values, which are given in the results chart, are valid for shank bolts with metric standard thread according to ISO 262; head dimensions of hexagonal bolts according to DIN EN ISO 4014 to 4018, hexalobular external driving head bolts according to DIN 34800 or cylindrical bolts according to DIN EN ISO 4762 and hole ”medium“ according to ISO 273 (DIN EN 20273).
Based on theory given in VDI standard, it's aimed to utilize the bolt strength to the greatest extent. Normally 90 % of minimum yield point (R_{p0.2min}) is allowed to be utilized. The default value for utilization factor is therefore set as 0.9 but can be changed.
The formulas used for metric bolt torque calculations are given in the List of Equations section. For more information about systematic procedure for calculating bolted joints in the form of calculated steps, visit VDI 2230.