Standard Tap Blank Dimensions
Reference USCTI Table 302
| Tap Size | Metric Equivalent | Overall Length | Thread Length | Square Length | Shank Diameter | Square Size |
|---|---|---|---|---|---|---|
| 0 | M1.6 | 1 5/8 | 5/16 | 3/16 | .141 | .110 |
| 1 | M1.8 | 1 11/16 | 3/8 | 3/16 | .141 | .110 |
| 2 | M2, M2.2 | 1 3/4 | 7/16 | 3/16 | .141 | .110 |
| 3 | M2.5 | 1 13/16 | 1/2 | 3/16 | .141 | .110 |
| 4 | — | 1 7/8 | 9/16 | 3/16 | .141 | .110 |
| 5 | M3, M3.15 | 1 15/16 | 5/8 | 3/16 | .141 | .110 |
| 6 | M3.5 | 2 | 11/16 | 3/16 | .141 | .110 |
| 8 | M4 | 2 1/8 | 3/4 | 1/4 | .168 | .131 |
| 10 | M4.5, M5 | 2 3/8 | 7/8 | 1/4 | .194 | .152 |
| 12 | — | 2 3/8 | 15/16 | 9/32 | .220 | .165 |
| 1/4 | M6, M6.3 | 2 1/2 | 1 | 5/16 | .255 | .191 |
| 5/16 | M7, M8 | 2 23/32 | 1 1/8 | 3/8 | .318 | .238 |
| 3/8 | M9, M10 | 2 15/16 | 1 1/4 | 7/16 | .381 | .286 |
| 7/16 | M11 | 3 5/32 | 1 7/16 | 13/32 | .323 | .242 |
| 1/2 | M12, M12.5 | 3 3/8 | 1 21/32 | 7/16 | .367 | .275 |
| 9/16 | M14 | 3 19/32 | 1 21/32 | 1/2 | .429 | .322 |
| 5/8 | M16 | 3 13/16 | 1 13/16 | 9/16 | .480 | .360 |
| 11/16 | M18 | 4 1/32 | 1 13/16 | 5/8 | .542 | .406 |
| 3/4 | — | 4 1/4 | 2 | 11/16 | .590 | .442 |
| 13/16 | M20 | 4 15/32 | 2 | 11/16 | .652 | .489 |
| 7/8 | M22 | 4 11/16 | 2 7/32 | 3/4 | .697 | .523 |
| 15/16 | M24 | 4 29/32 | 2 7/32 | 3/4 | .760 | .570 |
| 1 | M25 | 5 1/8 | 2 1/2 | 13/16 | .800 | .600 |
| 1 1/16 Long | M27 | 5 1/8 | 2 1/2 | 7/8 | .896 | .672 |
| 1 1/16 Short | M27 | 4 | 1 1/2 | 7/8 | .896 | .672 |
| 1 1/8 Long | — | 5 7/16 | 2 9/16 | 7/8 | .896 | .672 |
| 1 1/8 Short | — | 4 | 1 1/2 | 7/8 | .896 | .672 |
| 1 3/16 Long | M30 | 5 7/16 | 2 9/16 | 1 | 1.021 | .766 |
| 1 3/16 Short | M30 | 4 | 1 1/2 | 1 | 1.021 | .766 |
| 1 1/4 Long | — | 5 3/4 | 2 9/16 | 1 | 1.021 | .766 |
| 1 1/4 Short | — | 4 | 1 1/2 | 1 | 1.021 | .766 |
| 1 5/16 Long | M33 | 5 3/4 | 2 9/16 | 1 1/16 | 1.108 | .831 |
| 1 5/16 Short | M33 | 4 | 1 1/2 | 1 | 1.108 | .831 |
| 1 3/8 Long | — | 6 1/16 | 3 | 1 1/16 | 1.108 | .831 |
| 1 3/8 Short | — | 4 | 1 1/2 | 1 | 1.108 | .831 |
| 1 7/16 Long | M36 | 6 1/16 | 3 | 1 1/8 | 1.233 | .925 |
| 1 7/16 Short | M36 | 4 | 1 1/2 | 1 | 1.233 | .925 |
| 1 1/2 Long | M38 | 6 3/8 | 3 | 1 1/8 | 1.233 | .925 |
| 1 1/2 Short | M38 | 4 | 1 1/2 | 1 | 1.233 | .925 |
| 1 5/8 Long | M39 | 6 11/16 | 3 3/16 | 1 1/8 | 1.305 | .979 |
| 1 5/8 Short | M39 | 5 | 2 | 1 1/8 | 1.305 | .979 |
| 1 3/4 Long | M42 | 7 | 3 3/16 | 1 1/4 | 1.430 | 1.072 |
| 1 3/4 Short | M42 | 5 | 2 | 1 1/4 | 1.430 | 1.072 |
| 1 7/8 Long | M45 | 7 5/16 | 3 9/16 | 1 1/4 | 1.519 | 1.139 |
| 1 7/8 Short | M45 | 5 | 2 | 1 1/4 | 1.519 | 1.139 |
| 2 Long | M48 | 7 5/8 | 3 9/16 | 1 3/8 | 1.644 | 1.233 |
| 2 Short | M48 | 5 | 2 | 1 3/8 | 1.644 | 1.233 |
| 2 1/8 Long | — | 8 | 3 9/16 | 1 3/8 | 1.769 | 1.327 |
| 2 1/8 Short | — | 5 1/4 | 2 | 1 3/8 | 1.769 | 1.327 |
| 2 1/4 Long | M56 | 8 1/4 | 3 9/16 | 1 7/16 | 1.894 | 1.420 |
| 2 1/4 Short | M56 | 5 1/4 | 2 | 1 7/16 | 1.894 | 1.420 |
| 2 3/8 Long | — | 8 1/2 | 4 | 1 7/16 | 2.019 | 1.514 |
| 2 3/8 Short | — | 5 1/4 | 2 | 1 7/16 | 2.019 | 1.514 |
| 2 1/2 Long | — | 8 3/4 | 4 | 1 1/2 | 2.100 | 1.575 |
| 2 1/2 Short | — | 5 1/4 | 2 | 1 1/2 | 2.100 | 1.575 |
| 2 5/8 Long | M64 | 8 3/4 | 4 | 1 1/2 | 2.225 | 1.669 |
| 2 5/8 Short | M64 | 5 1/2 | 2 | 1 1/2 | 2.100 | 1.575 |
| 2 3/4 Long | — | 9 1/4 | 4 | 1 9/16 | 2.350 | 1.762 |
| 2 3/4 Short | — | 5 1/2 | 2 | 1 1/2 | 2.100 | 1.575 |
| 2 7/8 Long | M72 | 9 1/4 | 4 | 1 9/16 | 2.475 | 1.856 |
| 2 7/8 Short | M72 | 5 1/2 | 2 | 1 1/2 | 2.100 | 1.575 |
| 3 Long | — | 9 3/4 | 4 9/16 | 1 5/8 | 2.543 | 1.907 |
| 3 Short | — | 5 1/2 | 2 | 1 1/2 | 2.100 | 1.575 |
General Dimensions
| Dimensions - Inches | ||||||
|---|---|---|---|---|---|---|
| Nominal Size Inches |
Length Overall L |
Length of Thread l |
Length of Square l₂ |
Dia. of Shank d₁ |
Size of Square a |
Length Optional Neck l₁ |
| 1/16 | 2.13 | .69 | .38 | .3125 | .234 | .375 |
| 1/8 | 2.13 | .75 | .38 | .3125 | .234 | ... |
| 1/8 | 2.13 | .75 | .38 | .4375 | .328 | .375 |
| 1/4 | 2.44 | 1.06 | .44 | .5625 | .421 | .375 |
| 3/8 | 2.56 | 1.06 | .50 | .7000 | .531 | .375 |
| 1/2 | 3.13 | 1.38 | .63 | .6875 | .515 | ... |
| 3/4 | 3.25 | 1.38 | .69 | .9063 | .679 | ... |
| 1" | 3.75 | 1.75 | .81 | 1.1250 | .843 | ... |
| 1-1/4 | 4.00 | 1.75 | .94 | 1.3125 | .984 | ... |
| 1-1/2 | 4.25 | 1.75 | 1.00 | 1.5000 | 1.125 | ... |
| 2" | 4.25 | 1.75 | 1.13 | 1.8750 | 1.406 | ... |
| 2-1/2 | 5.50 | 2.56 | 1.25 | 2.2500 | 1.687 | ... |
| 3" | 6.00 | 2.63 | 1.38 | 2.6250 | 1.968 | ... |
| 3-1/2 | 6.50 | 2.69 | 1.50 | 2.8125 | 2.108 | ... |
| 4" | 6.75 | 2.75 | 1.56 | 3.0000 | 2.250 | ... |
Tolerances
| Element | Range | Direction | Tolerance |
|---|---|---|---|
| Length Overall – L | 1/16 to 3/4 inc. | Plus or Minus | .031 |
| 1" to 4" inc. | Plus or Minus | .063 | |
| Length of Thread – l | 1/16 to 3/4 inc. | Plus or Minus | .063 |
| 1" to 1-1/4 inc. | Plus or Minus | .094 | |
| 1-1/2 to 4" | Plus or Minus | .125 | |
| Length of Square - l₂ | 1/16 to 3/4 inc. | Plus or Minus | .031 |
| 1" to 4" inc. | Plus or Minus | .063 | |
| Diameter of Shank - | 1/16 to 1/8 | Minus | .0015 |
| 1/4 to 1" inc. | Minus | .0020 | |
| 1-1/4 to 4" inc. | Minus | .0030 | |
| Size of Square – a | 1/16 to 1/8 | Minus | .004 |
| 1/4 to 3/4 inc. | Minus | .006 | |
| 1" to 4" inc. | Minus | .008 |
Note
For thread limits and tolerances see Tables 335,335A and 338.
For eccentricity tolerances of taps see Table 317.
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