Threads / Series directory
UNC
thread sizes.
25 distinct nominal diameter–pitch combinations. Open a size for its differences and exact next steps.
Choose the complete designation
19 of 25 sizes have a matching reviewed drill-chart row. Other sizes provide an equation estimate with no rounded drill recommendation.
Swipe to see all columns →
| Designation | Major Ø · in / mm | TPI | Pitch · mm | Drill evidence | Next step |
|---|---|---|---|---|---|
| #1-64 UNC | 0.073 / 1.8542 | 64 | 0.396875 | Chart row | Tap-drill lookup → |
| #2-56 UNC | 0.086 / 2.1844 | 56 | 0.453571 | Chart row | Tap-drill lookup → |
| #3-48 UNC | 0.099 / 2.5146 | 48 | 0.529167 | Chart row | Tap-drill lookup → |
| #4-40 UNC | 0.112 / 2.8448 | 40 | 0.635 | Chart row | Tap-drill lookup → |
| #5-40 UNC | 0.125 / 3.175 | 40 | 0.635 | Chart row | Tap-drill lookup → |
| #6-32 UNC | 0.138 / 3.5052 | 32 | 0.79375 | Chart row | Tap-drill lookup → |
| #8-32 UNC | 0.164 / 4.1656 | 32 | 0.79375 | Chart row | Tap-drill lookup → |
| #10-24 UNC | 0.19 / 4.826 | 24 | 1.058333 | Chart row | Tap-drill lookup → |
| #12-24 UNC | 0.216 / 5.4864 | 24 | 1.058333 | Chart row | Tap-drill lookup → |
| 1/4-20 UNC | 0.25 / 6.35 | 20 | 1.27 | Chart row | Tap-drill lookup → |
| 5/16-18 UNC | 0.3125 / 7.9375 | 18 | 1.411111 | Chart row | Tap-drill lookup → |
| 3/8-16 UNC | 0.375 / 9.525 | 16 | 1.5875 | Chart row | Tap-drill lookup → |
| 7/16-14 UNC | 0.4375 / 11.1125 | 14 | 1.814286 | Chart row | Tap-drill lookup → |
| 1/2-13 UNC | 0.5 / 12.7 | 13 | 1.953846 | Chart row | Tap-drill lookup → |
| 9/16-12 UNC | 0.5625 / 14.2875 | 12 | 2.116667 | Chart row | Tap-drill lookup → |
| 5/8-11 UNC | 0.625 / 15.875 | 11 | 2.309091 | Chart row | Tap-drill lookup → |
| 3/4-10 UNC | 0.75 / 19.05 | 10 | 2.54 | Chart row | Tap-drill lookup → |
| 7/8-9 UNC | 0.875 / 22.225 | 9 | 2.822222 | Chart row | Tap-drill lookup → |
| 1-8 UNC | 1 / 25.4 | 8 | 3.175 | Chart row | Tap-drill lookup → |
| 1 1/8-7 UNC | 1.125 / 28.575 | 7 | 3.628571 | Equation only | Tap-drill lookup → |
| 1 1/4-7 UNC | 1.25 / 31.75 | 7 | 3.628571 | Equation only | Tap-drill lookup → |
| 1 3/8-6 UNC | 1.375 / 34.925 | 6 | 4.233333 | Equation only | Tap-drill lookup → |
| 1 1/2-6 UNC | 1.5 / 38.1 | 6 | 4.233333 | Equation only | Tap-drill lookup → |
| 1 3/4-5 UNC | 1.75 / 44.45 | 5 | 5.08 | Equation only | Tap-drill lookup → |
| 2-4 1/2 UNC | 2 / 50.8 | 4.5 | 5.644444 | Equation only | Tap-drill lookup → |
Before treating a size as a match
Confirm pitch, thread profile and complete drawing requirements. A nominal diameter match does not establish mating compatibility.
Read the designation and class →