| Size - Threads /Inch | Series | Tap Drill | Clearance Drill | Nut Points | Nut Flats | Washer I.D. | Washer O.D. | |
| Decimal (inches) | Number | |||||||
| 0-80 | UNF | 0.046 | 0.070 | 50 | 0.180 | 0.156 | 0.068 | 0.188 |
| 1-64 | UNC | 0.056 | 0.081 | 46 | 0.180 | 0.156 | 0.084 | 0.219 |
| 1-72 | UNF | 0.058 | 0.081 | 46 | 0.180 | 0.156 | 0.084 | 0.219 |
| 2-56 | UNC | 0.067 | 0.096 | 41 | 0.217 | 0.187 | 0.094 | 0.250 |
| 2-64 | UNF | 0.069 | 0.096 | 41 | 0.217 | 0.187 | 0.094 | 0.250 |
| 3-48 | UNC | 0.076 | 0.110 | 35 | 0.217 | 0.187 | 0.109 | 0.312 |
| 3-56 | UNF | 0.080 | 0.110 | 35 | 0.217 | 0.187 | 0.109 | 0.312 |
| 4-40 | UNC | 0.085 | 0.129 | 30 | 0.289 | 0.250 | 0.125 | 0.375 |
| 4-48 | UNF | 0.089 | 0.129 | 30 | 0.289 | 0.250 | 0.125 | 0.375 |
| 5-40 | UNC | 0.098 | 0.136 | 29 | 0.289 | 0.250 | 0.141 | 0.406 |
| 5-44 | UNF | 0.100 | 0.136 | 29 | 0.289 | 0.250 | 0.141 | 0.406 |
| 6-32 | UNC | 0.104 | 0.150 | 25 | 0.361 | 0.312 | 0.156 | 0.438 |
| 6-40 | UNF | 0.111 | 0.150 | 25 | 0.361 | 0.312 | 0.156 | 0.438 |
| 8-32 | UNC | 0.130 | 0.177 | 16 | 0.397 | 0.344 | 0.188 | 0.500 |
| 8-36 | UNF | 0.134 | 0.177 | 16 | 0.397 | 0.344 | 0.188 | 0.500 |
| 10-24 | UNC | 0.145 | 0.201 | 7 | 0.433 | 0.375 | 0.203 | 0.562 |
| 10-32 | UNF | 0.156 | 0.201 | 7 | 0.433 | 0.375 | 0.203 | 0.562 |
| 12-24 | UNC | 0.171 | 0.228 | 1 | 0.433 | 0.438 | 0.234 | 0.625 |
| 12-28 | UNF | 0.177 | 0.228 | 1 | 0.433 | 0.438 | 0.234 | 0.625 |
| 1/4-20 | UNC | 0.196 | 0.266 | H | 0.505 | 0.438 | 0.281 | 0.734 |
| 1/4-28 | UNF | 0.211 | 0.266 | H | 0.505 | 0.438 | 0.281 | 0.734 |
| 5/16-18 | UNC | 0.252 | 0.332 | Q | 0.577 | 0.500 | 0.344 | 0.875 |
| 5/16-24 | UNF | 0.267 | 0.332 | Q | 0.577 | 0.500 | 0.344 | 0.875 |
| 3/8-16 | UNC | 0.307 | 0.397 | X | 0.650 | 0.562 | 0.406 | 1.000 |
| 3/8-24 | UNF | 0.330 | 0.397 | X | 0.650 | 0.562 | 0.406 | 1.000 |
| 7/16-14 | UNC | 0.360 | 0.469 | 15/32 | 0.794 | 0.688 | 0.469 | 1.125 |
| 7/16-20 | UNF | 0.383 | 0.469 | 15/32 | 0.794 | 0.688 | 0.469 | 1.125 |
| 1/2-13 | UNC | 0.417 | 0.531 | 17/32 | 0.866 | 0.750 | 0.531 | 1.250 |
| 1/2-20 | UNF | 0.446 | 0.531 | 17/32 | 0.866 | 0.750 | 0.531 | 1.250 |
| 9/16-12 | UNC | 0.472 | 0.594 | 19/32 | 1.010 | 0.875 | 0.594 | 1.469 |
| 9/16-18 | UNF | 0.502 | 0.594 | 19/32 | 1.010 | 0.875 | 0.594 | 1.469 |
| 5/8-11 | UNC | 0.527 | 0.656 | 21/32 | 1.083 | 0.938 | 0.656 | 1.750 |
| 5/8-18 | UNF | 0.565 | 0.656 | 21/32 | 1.083 | 0.938 | 0.656 | 1.750 |
| 3/4-10 | UNC | 0.642 | 0.781 | 25/32 | 1.299 | 1.125 | 0.812 | 2.000 |
| 3/4-16 | UNF | 0.682 | 0.781 | 25/32 | 1.299 | 1.125 | 0.812 | 2.000 |
| 7/8-9 | UNC | 0.755 | 0.906 | 29/32 | 1.516 | 1.312 | 0.938 | 2.250 |
| 7/8-14 | UNF | 0.798 | 0.906 | 29/32 | 1.516 | 1.312 | 0.938 | 2.250 |
| 1-8 | UNC | 0.865 | 1.031 | 1 1/32 | 1.732 | 1.500 | 1.062 | 2.500 |
| 1-12 | UNF | 0.910 | 1.031 | 1 1/32 | 1.732 | 1.500 | 1.062 | 2.500 |
| 1-14 | UN | 1.031 | 1 1/32 | 1.732 | 1.500 | 1.062 | 2.500 | |
| 1 1/8-7 | UNC | 0.970 | 1.156 | 1 5/32 | 1.949 | 1.688 | 1.188 | 2.750 |
| 1 1/8-8 | UN | 1.156 | 1 5/32 | 1.949 | 1.688 | 1.188 | 2.750 | |
| 1 1/8-12 | UNF | 1.035 | 1.156 | 1 5/32 | 1.949 | 1.688 | 1.188 | 2.750 |
| 1 1/4-7 | UNC | 1.095 | 1.281 | 1 9/32 | 2.165 | 1.875 | 1.310 | 3.000 |
| 1 1/4-8 | UN | 1.281 | 1 9/32 | 2.165 | 1.875 | 1.310 | 3.000 | |
| 1 1/4-12 | UNF | 1.160 | 1.281 | 1 9/32 | 2.165 | 1.875 | 1.310 | 3.000 |
| 1 3/8-6 | UNC | 1.195 | 1.406 | 1 13/32 | 2.382 | 2.062 | 1.438 | 3.250 |
| 1 3/8-8 | UN | 1.406 | 1 13/32 | 2.382 | 2.062 | 1.438 | 3.250 | |
| 1 3/8-12 | UNF | 1.285 | 1.406 | 1 13/32 | 2.382 | 2.062 | 1.438 | 3.250 |
| 1 1/2-6 | UNC | 1.320 | 1.531 | 1 17/32 | 2.598 | 2.250 | 1.562 | 3.500 |
| 1 1/2-8 | UN | 1.531 | 1 17/32 | 2.598 | 2.250 | 1.562 | 3.500 | |
| 1 1/2-12 | UNC | 1.410 | 1.531 | 1 17/32 | 2.598 | 2.250 | 1.562 | 3.500 |
| 1 5/8-8 | UN | 1.656 | 1 21/32 | 2.815 | 2.438 | 1.750 | 3.750 | |
| 1 3/4-5 | UNC | 1.534 | 1.781 | 1 25/32 | 3.031 | 2.625 | 1.875 | 4.000 |
| 1 3/4-8 | UN | 1.781 | 1 25/32 | 3.031 | 2.625 | 1.875 | 4.000 | |
| 1 7/8-8 2-4 1/2 2-8 2 1/4-4.5 2 1/4-8 | UN UNC UN UNC UN | |||||||
| 2 1/2-4 2 1/2-8 2 3/4-4 2 3/4-8 3-4 | UNC UN UNC UN UNC | |||||||
| 3-8 3 1/4-4 3 1/4-8 3 1/2-4 3 1/2-8 | UN UNC UN UNC UN | |||||||
| 3 3/4-4 3 3/4-8 4-4 4-8 | UNC UN UNC UN | |||||||
1) See Drill Sizes page for cross reference. 2) Nut Points is the distance between opposite corners of hex nuts. 3) Nut Flats is the distance between opposite sides of hex nuts. |