Shop charts
Inch tap drills
UNC / UNF, #0 to 1/2 in. Drill designation with decimal inches.
Lavigne Labs
| Size – TPI | Series | Tap drill | Decimal in | Hard mat. | Decimal in | Close clear. | Decimal in | Free clear. | Decimal in |
|---|---|---|---|---|---|---|---|---|---|
| #0-80 | UNF | #56 | ⌀0.0465 | #55 | ⌀0.052 | #52 | ⌀0.0635 | #50 | ⌀0.07 |
| #1-64 | UNC | #53 | ⌀0.0595 | #53 | ⌀0.0595 | #48 | ⌀0.076 | #46 | ⌀0.081 |
| #1-72 | UNF | #53 | ⌀0.0595 | 1/16 | ⌀0.0625 | #48 | ⌀0.076 | #46 | ⌀0.081 |
| #2-56 | UNC | #50 | ⌀0.07 | #50 | ⌀0.07 | #43 | ⌀0.089 | #41 | ⌀0.096 |
| #2-64 | UNF | #50 | ⌀0.07 | #49 | ⌀0.073 | #43 | ⌀0.089 | #41 | ⌀0.096 |
| #3-48 | UNC | #47 | ⌀0.0785 | #46 | ⌀0.081 | #37 | ⌀0.104 | #35 | ⌀0.11 |
| #3-56 | UNF | #45 | ⌀0.082 | #45 | ⌀0.082 | #37 | ⌀0.104 | #35 | ⌀0.11 |
| #4-40 | UNC | #43 | ⌀0.089 | #43 | ⌀0.089 | #32 | ⌀0.116 | #30 | ⌀0.1285 |
| #4-48 | UNF | #42 | ⌀0.0935 | 3/32 | ⌀0.0938 | #32 | ⌀0.116 | #30 | ⌀0.1285 |
| #5-40 | UNC | #38 | ⌀0.1015 | #37 | ⌀0.104 | #30 | ⌀0.1285 | #29 | ⌀0.136 |
| #5-44 | UNF | #37 | ⌀0.104 | #36 | ⌀0.1065 | #30 | ⌀0.1285 | #29 | ⌀0.136 |
| #6-32 | UNC | #36 | ⌀0.1065 | #34 | ⌀0.111 | #27 | ⌀0.144 | #25 | ⌀0.1495 |
| #6-40 | UNF | #33 | ⌀0.113 | #32 | ⌀0.116 | #27 | ⌀0.144 | #25 | ⌀0.1495 |
| #8-32 | UNC | #29 | ⌀0.136 | #29 | ⌀0.136 | #18 | ⌀0.1695 | #16 | ⌀0.177 |
| #8-36 | UNF | #29 | ⌀0.136 | #28 | ⌀0.1405 | #18 | ⌀0.1695 | #16 | ⌀0.177 |
| #10-24 | UNC | #25 | ⌀0.1495 | #23 | ⌀0.154 | #9 | ⌀0.196 | #7 | ⌀0.201 |
| #10-32 | UNF | #21 | ⌀0.159 | #19 | ⌀0.166 | #9 | ⌀0.196 | #7 | ⌀0.201 |
| #12-24 | UNC | #16 | ⌀0.177 | #15 | ⌀0.18 | #2 | ⌀0.221 | #1 | ⌀0.228 |
| #12-28 | UNF | #14 | ⌀0.182 | #13 | ⌀0.185 | #2 | ⌀0.221 | #1 | ⌀0.228 |
| 1/4-20 | UNC | #7 | ⌀0.201 | #4 | ⌀0.209 | F | ⌀0.257 | H | ⌀0.266 |
| 1/4-28 | UNF | #3 | ⌀0.213 | 7/32 | ⌀0.2188 | F | ⌀0.257 | H | ⌀0.266 |
| 5/16-18 | UNC | F | ⌀0.257 | 17/64 | ⌀0.2656 | P | ⌀0.323 | Q | ⌀0.332 |
| 5/16-24 | UNF | I | ⌀0.272 | J | ⌀0.277 | P | ⌀0.323 | Q | ⌀0.332 |
| 3/8-16 | UNC | 5/16 | ⌀0.3125 | P | ⌀0.323 | W | ⌀0.386 | X | ⌀0.397 |
| 3/8-24 | UNF | Q | ⌀0.332 | R | ⌀0.339 | W | ⌀0.386 | X | ⌀0.397 |
| 7/16-14 | UNC | U | ⌀0.368 | V | ⌀0.377 | 29/64 | ⌀0.4531 | 15/32 | ⌀0.4688 |
| 7/16-20 | UNF | 25/64 | ⌀0.3906 | X | ⌀0.397 | 29/64 | ⌀0.4531 | 15/32 | ⌀0.4688 |
| 1/2-13 | UNC | 27/64 | ⌀0.4219 | 7/16 | ⌀0.4375 | 33/64 | ⌀0.5156 | 17/32 | ⌀0.5312 |
| 1/2-20 | UNF | 29/64 | ⌀0.4531 | 29/64 | ⌀0.4531 | 33/64 | ⌀0.5156 | 17/32 | ⌀0.5312 |
Tap drill in the red column is the standard (about 75%) drill; the hard-material column is the next size up. Close and free are clearance-hole fits.
How to use
How to pick an inch tap drill:
- Find the thread. Locate the screw size and threads per inch (for example 1/4-20 UNC) in the Size – TPI column.
- Read the tap drill. Use the Tap drill column for the drill designation (number, letter or fraction) and the Decimal in column for its diameter (1/4-20: #7, 0.201 in).
- Adjust for hard material. For hard or tough material use the Hard mat. column, the next drill size up.
- Drill, then tap. Drill to the full thread depth plus a few threads, deburr, then cut the thread with a tap and cutting fluid.
lavignelabs.net/tools/charts/inch-tap-drills/Lavigne Labs · verify against your own tooling before cutting