Holes and Counterbore Sizes

Metric SHCS Hole & Counterbore Sizes

Nominal Screw SizeClearance Hole Dia. mmCounterbore Dia. mmCountersink Dia. mmTapping Drill mm
 CloseNormal  ISOM Fine
M33.43.76.53.60.5
M44.44.88.254.70.7
M55.45.89.755.74.2
M66.46.811.256.85.0
M88.48.814.259.26.87.0
M1010.510.817.2511.28.58.8
M1212.512.819.2514.210.210.5
M1414.514.7522.2516.212.012.5
M1616.516.7525.518.214.014.5
M2020.520.7531.522.417.518.5
M2424.524.7537.526.421.022.0
M3030.7531.7547.533.426.5

Imperial SHCS Hole & Counterbore Sizes

Nominal Screw SizeClearance Hole Dia. mmCounterbore Dia. mmCountersink Dia. mmTapping Drill mm
 CloseNormal  UNFUNC
84.65.08.04.83.53.4
105.25.69.55.54.13.8
1/4″6.87.211.07.05.55.1
5/16″8.48.813.58.86.96.6
3/8″10.010.416.010.58.58.0
7/16″11.512.018.012.29.89.4
1/2″13.013.520.514.011.510.8
5/8″16.216.825.517.514.513.5
3/4″19.519.830.021.017.516.5
7/8″22.823.035.024.520.519.5
1″25.826.241.028.023.522.0
1 1/4″32.633.4503529.528.0