Primary Secondary D bsc UNC UNF UNEF 4-UN 6-UN 8-UN 12-UN 16-UN 20-UN 28-UN 32-UN Nominal 0 * 0.06 * 80 * * * * * * * * * 0 * 1 0.073 64 72 * * * * * * * * * 1 2 * 0.086 56 64 * * * * * * * * * 2 * 3 0.099 48 56 * * * * * * * * * 3 4 * 0.112 40 48 * * * * * * * * * 4 5 * 0.125 40 44 * * * * * * * * * 5 6 * 0.138 32 40 * * * * * * * * UNC 6 8 * 0.164 32 36 * * * * * * * * UNC 8 10 * 0.19 24 32 * * * * * * * * UNF 10 * 12 0.216 24 28 32 * * * * * * UNF UNEF 12 1/4 * 0.25 20 28 32 * * * * * UNC UNF UNEF 1/4 5/16 * 0.3125 18 24 32 * * * * * 20 28 UNEF 5/16 3/8 * 0.375 16 24 32 * * * * UNC 20 28 UNEF 3/8 7/16 * 0.4375 14 20 28 * * * * 16 UNF UNEF 32 7/16 1/2 * 0.5 13 20 28 * * * * 16 UNF UNEF 32 1/2 9/16 * 0.5625 12 I8 24 * * * UNC 16 20 28 32 9/16 5/8 * 0.625 11 18 24 * * * 12 16 20 28 32 5/8 * 11/16 0.6875 * * 24 * * * 12 16 20 28 32 11/16 3/4 * 0.75 10 16 20 * * * 12 UNF UNEF 28 32 3/4 * 13/16 0.8125 * * 20 * * * 12 16 UNEF 28 32 13/16 7/8 * 0.875 9 14 20 * * * 12 16 UNEF 28 32 7/8 * 15/16 0.9375 * * 20 * * * 12 16 UNEF 28 32 15/16 1 * 1 8 12 20 * * UNC UNF 16 UNEF 28 32 1 * 11/16 1.0625 * * 18 * * 8 12 16 20 28 * 1-1/16 11/8 * 1.125 7 12 18 * * 8 UNF 16 20 28 * 1-1/8 * 13/16 1.1875 * * 18 * * 8 12 16 20 28 * 1-3/16 11/4 * 1.25 7 12 18 * * 8 UNF 16 20 28 * 1-1/4 * 15/16 1.3125 * * 18 * * 8 12 16 20 28 * 1-5/16 13/8 * 1.375 6 12 18 * UNC 8 UNF 16 20 28 * 1-3/8 * 17/16 1.4375 * * 18 * 6 8 12 16 20 28 * 1-7/16 11/2 * 1.5 6 12 18 * UNC 8 UNF 16 20 28 * 1-1/2 * 19/16 1.5625 * * 18 * 6 8 12 16 20 * * 1-9/16 15/8 * 1.625 * * 18 * 6 8 12 16 20 * * 1-5/8 * 111/16 1.6875 * * 18 * 6 8 12 16 20 * * 1-11/16 13/4 * 1.75 5 * * * 6 8 12 16 20 * * 1-3/4 * 113/16 1.8125 * * * * 6 8 12 16 20 * * 1-13/16 17/8 * 1.875 * * * * 6 8 12 16 20 * * 1-7/8 * 115/16 1.9375 * * * * 6 8 12 16 20 * * 1-15/16 2 * 2 41/2 * * * 6 8 12 16 20 * * 2 * 21/8 2.125 * * * * 6 8 12 16 20 * * 2-1/8 21/4 * 2.25 41/2 * * * 6 8 12 16 20 * * 2-1/4 * 23/8 2.375 * * * * 6 8 12 16 20 * * 2-3/8 21/2 * 2.5 4 * * UNC 6 8 12 16 20 * * 2-1/2 * 25/8 2.625 * * * 4 6 8 12 16 20 * * 2-5/8 23/4 * 2.75 4 * * UNC 6 8 12 16 20 * * 2-3/4 * 27/8 2.875 * * * 4 6 8 12 16 20 * * 2-7/8 3 * 3 4 * * UNC 6 8 12 16 20 * * 3 * 31/8 3.125 * * * 4 6 8 12 16 * * * 3-1/8 31/4 * 3.25 4 * * UNC 6 8 12 16 * * * 3-1/4 * 33/8 3.375 * * * 4 6 8 12 16 * * * 3-3/8 31/2 * 3.5 4 * * UNC 6 8 12 16 * * * 3-1/2 * 35/8 3.625 * * * 4 6 8 12 16 * * * 3-5/8 33/4 * 3.75 4 * * UNC 6 8 12 16 * * * 3-3/4 * 37/8 3.875 * * * 4 6 8 12 16 * * * 3-7/8 4 * 4 4 * * UNC 6 8 12 1.6 * * * 4 * 41/8 4.125 * * * 4 6 8 12 16 * * * 4-1/8 41/4 * 4.25 * * * 4 6 8 12 16 * * * 4-1/4 * 43/8 4.375 * * * 4 6 8 12 16 * * * 4-3/8 41/2 * 4.5 * * * 4 6 8 12 16 * * * 4-1/2 * 45/8 4.625 * * * 4 6 8 12 16 * * * 4-5/8 43/4 * 4.75 * * * 4 6 8 12 16 16 * * 4-3/4 * 47/8 4.875 * * * 4 6 8 12 16 * * * 4-7/8 5 * 5 * * * 4 6 8 12 16 * * * 5 * 51/8 5.125 * * * 4 6 8 12 16 * * * 5-1/8 51/4 * 5.25 * * * 4 6 8 12 16 * * * 5-1/4 * 53/8 5.375 * * * 4 6 8 12 16 * * * 5-3/8 51/2 * 5.5 * * * 4 6 8 12 16 * * * 5-1/2 * 55/8 5.625 * * * 4 6 8 12 16 * * * 5-5/8 53/4 * 5.75 * * * 4 6 8 12 16 * * * 5-3/4 * 57/8 5.875 * * * 4 6 8 12 16 * * * 5-7/8 6 * 6 * * * 4 6 8 12 16 * * * 6