ThreadDiam(mm) Pitch(mm) HoleDiam(mm) Ref. DESC_IN_DRAFTING 7.72 0.907 6.56 G 1/16" 9.73 0.907 8.80 G 1/8" 13.16 1.337 11.80 G 1/4" 16.66 1.337 15.25 G 3/8" 20.95 1.814 19.00 G 1/2" 22.91 1.814 21.00 G 5/8" 26.44 1.814 24.50 G 3/4" 30.20 1.814 28.25 G 7/8" 33.25 2.309 30.75 G 1" 37.90 2.309 35.30 G 1 1/8" 41.91 2.309 39.25 G 1 1/4" 44.32 2.309 41.70 G 1 3/8" 47.80 2.309 45.25 G 1 1/2" 53.74 2.309 51.10 G 1 3/4" 59.61 2.309 57.00 G 2" 65.71 2.309 63.10 G 2 1/4" 75.18 2.309 72.60 G 2 1/2" 81.53 2.309 78.90 G 2 3/4" 87.88 2.309 85.30 G 3" 93.98 2.309 91.50 G 3 1/4" 100.33 2.309 97.70 G 3 1/2" 106.68 2.309 104.00 G 3 3/4" 113.03 2.309 110.40 G 4" 138.43 2.31 135.37 G 5" 163.83 2.31 160.87 G 6"