| NPT Size | Tap Drill Size (in.) | Decimal Equivalent (in.) |
|---|---|---|
| 1/16 – 27 | C | 0.242 |
| 1/8 – 27 | Q | 0.332 |
| 1/4 – 18 | 7/16 | 0.438 |
| 3/8 – 18 | 9/16 | 0.562 |
| 1/2 – 14 | 45/64 | 0.703 |
| 3/4 – 14 | 29/32 | 0.906 |
| 1 – 11 – 1/2 | 1-9/64 | 1.141 |
| 1 – 1/4 – 11 – 1/2 | 1-31/64 | 1.484 |
| 1 – 1/2 – 11 – 1/2 | 1-23/32 | 1.719 |
| 2 – 11 – 1/2 | 2-3/16 | 2.188 |
| 2 – 1/2 – 8 | 2-39/64 | 2.609 |
| 3 – 8 | 3-15/64 | 3.234 |
Standard NPT Tap Drill Sizes and Decimal Equivalents
Find the complete standard NPT tap drill sizes chart, including decimal equivalents for accurate conversions. Easily reference tap drill sizes from 1/16 to 3 inches for precise machining and threading applications.