Minimum Drilling Depth for Taps
THREAD SIZE DRILL SIZE PLUG
TAPS		 BOTTOMING TAPS
ALUMINUM STEEL/
MAG/
PLASTIC		 1 DIA 1-1/2 DIA 2 DIA  2-1/2 DIA 3 DIA 1 DIA 1-1/2 DIA 2 DIA 2-1/2 DIA 3.0
UNIFIED COARSE
1 (.073)-64 #47 (.0785) #46 (.0810) .203 .240 .276 .313 .349 .136 .172 .209 .245 .282
2 (.086)-56 3/32 (.0938) #41 (.0960) .236 .279 .322 .365 .408 .157 .200 .243 .286 .329
3 (.099)-48 #36 (.1065) 7/64 (.1094) .273 .323 .372 .422 .471 .182 .232 .281 .331 .380
4 (.112)-40 #31 (.1200) #31 (.1200) .318 .374 .430 .486 .542 .212 .268 .324 .380 .436
5 (.125)-40 3.4 MM (.1339) #29 (.1360) .338 .400 .462 .525 .588 .225 .288 .350 .412 .475
6 (.138)-32 #26 (.1470) #25 (.1495) .394 .464 .532 .602 .670 .263 .332 .401 .470 .539
8 (.164)-32 #17 (.1730) #16 (.1770) .434 .516 .598 .680 .762 .289 .371 .453 .535 .617
10 (.190)-24 13/64 (.2031) #5 (.2055) .535 .630 .725 .820 .915 .357 .452 .547 .642 .737
12 (.216)-24* #1 (.2280) #1 (.2280) .574 .682 .790 .898 1.006 .383 .491 .599 .707 .815
1/4 (.2500)-20 H (.2660) H (.2660) .675 .800 .925 1.050 1.175 .450 .575 .700 .825 .950
5/16 (.3125)-18 Q (.3320) Q (.3320) .801 .957 1.113 1.269 1.425 .534 .690 .846 1.002 1.158
3/8 (.3750)-16 X (.3970) X (.3970) .750 .938 1.125 1.312 1.500 .625 .812 1.000 1.188 1.375
7/16 (.4375)-14 29/64 (.4531) 29/64 (.4531) .867 1.086 1.305 1.524 1.743 .724 .943 1.162 1.381 1.600
1/2 (.5000)-13* 33/64 (.5156) 17/32 (.5312) .962 1.212 1.462 1.712 1.962 .808 1.058 1.308 1.558 1.808
9/16 (.5625)-12* 37/64 (.5781) 19/32 (.5938) 1.062 1.343 1.624 1.905 2.186 .895 1.176 1.457 1.738 2.019
5/8 (.6250)-11 21/32 (.6562) 21/32 (.6562) 1.170 1.483 1.795 2.108 2.420 .989 1.301 1.614 1.926 2.239
3/4 (.7500)-10 25/32 (.7812) 25/32 (.7812) 1.350 1.725 2.100 2.475 2.850 1.150 1.525 1.900 2.275 2.650
7/8 (.8750)-9 29/32 (.9062) 29/32 (.9062) 1.542 1.979 2.417 2.854 3.292 1.319 1.757 2.194 2.632 3.069
1 (1.000)-8 1-1/32 (1.0312) 1-1/32 (1.0312) 1.750 2.250 2.750 3.250 3.750 1.500 2.000 2.500 3.000 3.500
1-1/8 (1.1250)-7 1-11/64 (1.1719) 1-11/64 (1.1719) 1.982 2.545 3.107 3.670 4.232 1.696 2.259 2.821 3.384 3.946
1-1/4 (1.2500)-7 1-19/64 (1.2969) 1-19/64 (1.2969) 2.107 2.732 3.357 3.982 4.607 1.821 2.446 3.071 3.696 4.321
1-3/8 (1.3750)-6 1-27/64 (1.4219) 1-27/64 (1.4219) 2.375 3.062 3.750 4.437 5.125 2.042 2.729 3.417 4.104 4.792
1-1/2 (1.5000)-6 1-35/64 (1.5469) 1-35/64 (1.5469) 2.500 3.250 4.000 4.750 5.500 2.167 2.917 3.667 4.417 5.167
UNITED FINE
2 (.086)-64 2.35MM (.0925) 2.35MM (.0925) .223 .266 .309 .352 .395 .149 .192 .235 .278 .321
3 (.099)-56 #37 (.1040) #36 (.1065) .256 .305 .355 .404 .454 .170 .220 .269 .319 .368
4 (.112)-48 3MM (.1181) #31 (.1200) .293 .349 .405 .461 .517 .195 .251 .307 .363 .419
6 (.138)-40 #26 (.1470) #25 (.1495) .357 .426 .495 .564 .633 .238 .307 .376 .445 .514
8 (.164)-36 #17 (.1730) #16 (.1770) .413 .495 .577 .659 .741 .275 .357 .439 .521 .603
10 (.190)-32 #7 (.2010) 13/64 (.2031) .472 .568 .662 .758 .852 .315 .410 .505 .600 .695
1/4 (.2500)-28 G (.2610) 6.7MM (.2638) .589 .714 .839 .964 1.089 .393 .518 .643 .768 .893
5/16 (.3125)-24 21/64 (.3281) 21/64 (.3281) .718 .874 1.030 1.186 1.342 .479 .635 .791 .947 1.103
3/8 (.3750)-24 25/64 (.3906) 25/64 (.3906) .625 .812 1.000 1.187 1.375 .542 .729 .917 1.104 1.292
7/16 (.4375)-20 29/64 (.4531 29/64 (.4531) .738 .957 1.176 1.395 1.614 .638 .857 1.076 1.295 1.514
1/2 (.5000)-20 33/64 (.5156) 33/64 (.5156) .800 1.050 1.300 1.550 1.800 .700 .950 1.200 1.450 1.700
9/16 (.5625)-18 37/64 (.5781) 37/64 (.5781) .895 1.176 1.457 1.738 2.019 .784 1.065 1.346 1.627 1.908
5/8 (.6250)-18 41/64 (.6406) 41/64 (.6406) .958 1.271 1.583 1.896 2.208 .847 1.160 1.472 1.785 2.097
3/4 (.7500)-16 49/64 (.7656) 49/64 (.7656) 1.125 1.500 1.875 2.250 2.625 1.000 1.375 1.750 2.125 2.500
7/8 (.8750)-14 57/64 (.8906) 57/64 (.8906) 1.304 1.741 2.179 2.616 3.054 1.161 1.598 2.036 2.473 2.911
1 (1.000)-14 1-1/64 (1.0156) 1-1/32 (1.0312) 1.429 1.929 2.429 2.929 3.429 1.286 1.786 2.286 2.786 3.286
1 (1.000)-12* 1-1/64 (1.0156) 1-1/32 (1.0312) 1.500 2.000 2.500 3.000 3.500 1.333 1.833 2.333 2.833 3.333
1-1/8 (1.1250)-12* 1-9/64 (1.1406) 1-5/32 (1.1562) 1.625 2.187 2.750 3.312 3.875 1.458 2.021 2.583 3.146 3.708
1-1/4 (1.2500)-12* 1-17/64 (1.2656) 1-9/32 (1.2812) 1.750 2.375 3.000 3.625 4.250 1.583 2.208 2.833 3.458 4.083
1-3/8 (1.3750)-12* 1-25/64 (1.3906) 1-13/32 (1.4062) 1.875 2.562 3.250 3.937 4.625 1.708 2.396 3.083 3.771 4.458
1-1/2 (1.5000)-12* 1-33/64 (1.5156) 1-17/32 (1.5312) 2.000 2.750 3.500 4.250 5.000 1.833 2.583 3.333 4.083 4.833