METRIC BOLT TORQUE VALUES CALCULATOR
Metric bolt torque values calculator has been developed 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.
Calculator:
RESULTS 
Parameter 
Symbol 
Value 
Unit 
Designation 
 


 
Property Class 
 


Screw Thread Series 
 


Utilization Factor 
v 


Assembly Preload 
F_{M,Tab} 


kN 
Tightening Torque 
M_{A} 


N.m 
Supplements:
Link 
Usage 
Metric Thread Size and Tolerance Calculator 
Calculates
basic major, minor and pitch diameters of the metric external (bolt) thread and
internal (nut) thread according to
ISO 724:1993 standard. In addition to basic size calculations, tolerance calculations
of different tolerance classes can be done according to
ISO 9651:1998 and ISO 9652:1998 standards. 
Friction Coefficient Guide Values in Bolted Joints 
The coefficients of friction values in the thread μ_{G} and in
the bearing surfaces of the head of the bolt or the nut μ_{K}. 
List of Equations:
Parameter/Condition 
Symbol 
Equation 
Tightening Torque 
M_{A} 

Permissible Assembly Preload 
F_{Mzul} 

Effective diameter for the friction moment 
D_{Km} 

List of Parameters 
Symbol 
Definition 
P 
Pitch 
d_{2} 
Pitch diameter of the bolt thread 
d_{0} 
Diameter at the relevant smallest cross section 
d_{h} 
hole diameter of clamped parts 
s 
Width across flats 
μ_{Gmin} 
Coefficient of friction in the thread 
μ_{Kmin} 
Coefficient of friction in the head bearing area 
R_{p0.2} 
0,2% proof stress of the bolt according to DIN EN ISO 8981 
D_{Km} 
Effective diameter for the friction moment
at the bolt head or nut bearing area 
A_{0} 
Appropriate minimum crosssectional area
of the bolt 
Reference:
 VDI 2230– Systematic calculation of high duty bolted joints  Joints with one cylindrical bolt