TorqueCalcPhone app for iPhone and iPad

TorqueCalcPhone can easily calculate the tightening torque for metric bolts.

Secondary the minimum and maximum clamp load and the tightening factor alphaA is calculated. As additional information the diameter of the through hole, the bearing diameter of the bolt head is shown.

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The screw size can be entered for the range M3 to M64. When the slider of the pitch is on the leftmost position the standard pitch is used or in a other position various fine threads that available for the bolt size.


You can select the strength classes 8.8, 10.9 and 12.9.


Available are hexagon head bolts in accordance with ISO 4014 or Hexagon socket head cap screws in accordance with ISO 4762. Not available bolt sizes in the standard can not be selected.

For the through hole according to DIN EN 20273:1992-02 can be selected fine, medium or rough.


The minimum and maximum friction coefficient of the bolt is a important calculation parameter and therefore must be selected. It is not recommended to have a small range for the friction coefficients. A useful range for example according to VDA (German Association of the Automotive Industry) is 0.09 to 0.15. This range is reached only with lubricated bolts.

The tightening accuracy of the tool is also part of the calculation. A torque wrench according to DIN EN ISO 6789 has an accuracy of ± 4% or ± 6%. The accuracy of an impact wrench is significantly lower.


After calculating the results and input values are displayed on a separate page. The calculation can be documented by a screenshot.