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Major diameter (inch / mm) | Thread density (d, threads per inch) and thread pitch (p) | Preferred cutting tap drill size | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Coarse (UNC) | Fine (UNF) | Extra fine (UNEF) | ||||||||
d (TPI) | p (inch / mm) | d (TPI) | p (inch / mm) | d (TPI) | p (inch / mm) | Coarse | Fine | Extra fine | ||
#0 | 0.0600 / 1.5240 | None | 80 | 0.012500 / 0.3175 | None | 3⁄64 in (.047) | ||||
#1 | 0.0730 / 1.8542 | 64 | 0.015625 / 0.3969 | 72 | 0.013888 / 0.3528 | None | #53 (.060) | #53 (.060) | ||
#2 | 0.0860 / 2.1844 | 56 | 0.017857 / 0.4536 | 64 | 0.015625 / 0.3969 | None | #50 (.070) | #50 (.070) | ||
#3 | 0.0990 / 2.5146 | 48 | 0.020833 / 0.5292 | 56 | 0.017857 / 0.4536 | None | #47 (.079) | #45 (.082) | ||
#4 | 0.1120 / 2.8448 | 40 | 0.025000 / 0.6350 | 48 | 0.020833 / 0.5292 | None | #43 (.089) | #42 (.094) | ||
#5 | 0.1250 / 3.1750 | 40 | 0.025000 / 0.6350 | 44 | 0.022727 / 0.5773 | None | #38 (.102) | #37 (.104) | ||
#6 | 0.1380 / 3.5052 | 32 | 0.031250 / 0.7938 | 40 | 0.025000 / 0.6350 | None | #36 (.107) | #33 (.113) | ||
#8 | 0.1640 / 4.1656 | 32 | 0.031250 / 0.7938 | 36 | 0.027778 / 0.7056 | None | #29 (.136) | #29 (.136) | ||
#10 | 0.1900 / 4.8260 | 24 | 0.041667 / 1.0583 | 32 | 0.031250 / 0.7938 | None | #25 (.150) | #21 (.159) | ||
#12 | 0.2160 / 5.4864 | 24 | 0.041667 / 1.0583 | 28 | 0.035714 / 0.9071 | 32 | 0.031250 / 0.7938 | #16 (.177) | #14 (.182) | 3⁄16 in (.188) |
1⁄4″ | 0.2500 / 6.3500 | 20 | 0.050000 / 1.2700 | 28 | 0.035714 / 0.9071 | 32 | 0.031250 / 0.7938 | #7 (.201) | #3 (.213) | 7⁄32 in (.219) |
5⁄16″ | 0.3125 / 7.9375 | 18 | 0.055556 / 1.4111 | 24 | 0.041667 / 1.0583 | 32 | 0.031250 / 0.7938 | F (.257) | I (.272) | 9⁄32 in (.281) |
3⁄8″ | 0.3750 / 9.5250 | 16 | 0.062500 / 1.5875 | 24 | 0.041667 / 1.0583 | 32 | 0.031250 / 0.7938 | 5⁄16 in (.313) | Q (.332) | 11⁄32 in (.344) |
7⁄16″ | 0.4375 / 11.1125 | 14 | 0.071428 / 1.8143 | 20 | 0.050000 / 1.2700 | 28 | 0.035714 / 0.9071 | U (.368) | 25⁄64 in (.391) | Y (.404) |
1⁄2″ | 0.5000 / 12.7000 | 13 | 0.076923 / 1.9538 | 20 | 0.050000 / 1.2700 | 28 | 0.035714 / 0.9071 | 27⁄64 in (.422) | 29⁄64 in (.453) | 15⁄32 in (.469) |
9⁄16″ | 0.5625 / 14.2875 | 12 | 0.083333 / 2.1167 | 18 | 0.055556 / 1.4111 | 24 | 0.041667 / 1.0583 | 31⁄64 in (.484) | 1⁄2 in (.5) | 33⁄64 in (.516) |
5⁄8″ | 0.6250 / 15.8750 | 11 | 0.090909 / 2.3091 | 18 | 0.055556 / 1.4111 | 24 | 0.041667 / 1.0583 | 17⁄32 in (.531) | 9⁄16 in (.563) | 37⁄64 in (.578) |
3⁄4″ | 0.7500 / 19.0500 | 10 | 0.100000 / 2.5400 | 16 | 0.062500 / 1.5875 | 20 | 0.050000 / 1.2700 | 21⁄32 in (.656) | 11⁄16 in (.688) | 45⁄64 in (.703) |
7⁄8″ | 0.8750 / 22.2250 | 9 | 0.111111 / 2.8222 | 14 | 0.071428 / 1.8143 | 20 | 0.050000 / 1.2700 | 49⁄64 in (.766) | 51⁄64 in (.797) | 53⁄64 in (.828) |
1″ | 1.0000 / 25.4000 | 8 | 0.125000 / 3.1750 | 12(*) | 0.083333 / 2.1167 | 20 | 0.050000 / 1.2700 | 7⁄8 in (.875) | 59⁄64 in (.922) | 61⁄64 in (.953) |