Hole Sizes - Self-Tapping Screws - Metric

Recommended Hole Sizes for Metric Self-Tappers Type AB - to DIN 7975  

The following referance values are valid only for case hardened steel self-tapping screws applied in a simple fastening joint with clearance holes. The tightening torques are max. 50% of the minimum breaking torque. Prior test must be carried out for the utilisation of other screws or other sheet metal materials. Punched pilot holes must be 0/1 - 0.3mm larger and the screws must be tightened in the direction the hole was punched.

Thread diameterMaterial Strength Rm (N/mm2)Diameter of the pilot hole for thread dimensions ST 2.2 - ST6.3 for sheet metal thicknesses (mm)
0.80.911.11.21.31.41.51.61.71.81.922.22.52.833.544.55
ST 2.2from 1001.71.71.71.71.71.71.71.71.71.71.8          
approx. 3001.71.71.71.71.71.71.81.81.81.91.9          
up to 5001.71.71.71.81.81.81.81.71.91.91.9          
ST 2.9from 101   2.22.22.22.22.22.22.22.22.22.22.3       
approx. 301   2.22.22.22.22.32.32.32.42.42.42.4       
up to 501   2.22.22.32.32.42.42.42.42.52.52.5       
ST 3.5from 102     2.62.72.72.72.72.72.72.72.72.82.9     
approx. 302     2.62.72.72.72.72.82.82.92.933     
up to 502     2.72.82.82.92.92.92.9333.13.1     
ST 3.9from 103     2.92.933333333.13.23.3    
approx. 303     2.92.9333.13.13.23.23.23.33.33.3    
up to 503     33.13.13.23.23.33.33.33.33.43.43.5    
ST 4.2from 104      3.13.23.23.23.23.23.23.23.23.33.43.5   
approx. 304      3.13.23.23.23.33.33.43.43.53.63.63.6   
up to 504      3.33.33.43.43.43.43.53.53.63.63.63.7   
ST 4.8from 105        3.63.63.63.63.63.63.73.83.944.1  
approx. 305        3.63.73.83.83.93.944.14.14.24.2  
up to 505        3.93.94444.14.14.24.24.24.3  
ST 5.5from 106          4.24.24.24.24.24.44.54.64.74.8 
approx. 306          4.34.44.44.54.74.74.84.84.94.9 
up to 506          4.64.64.64.74.84.84.94.955 
ST 6.3from 107          4.94.94.94.955.25.35.45.55.65.7
approx. 307          55.15.25.35.45.55.65.75.75.85.8
up to 507          5.35.45.45.55.65.75.75.75.85.85.8

Note: Due to the fact that fastening applications differ greatly, the above information is for guidance only and is correct to the best of our knowledge. The customer must satisfy themselves with the performance of the fastener and validity of the data. TR Fastenings will not be held responsible for any failure that may occur from the use of this information.