Thread Pitch Chart
UNC / UNF
| Size | Major dia | UNC TPI | UNF TPI |
|---|---|---|---|
| #0 | 0.060 | 80 | - |
| #1 | 0.073 | 64 | 72 |
| #2 | 0.086 | 56 | 64 |
| #3 | 0.099 | 48 | 56 |
| #4 | 0.112 | 40 | 48 |
| #5 | 0.125 | 40 | 44 |
| #6 | 0.138 | 32 | 40 |
| #8 | 0.164 | 32 | 36 |
| #10 | 0.190 | 24 | 32 |
| #12 | 0.216 | 24 | 28 |
| 1/4 | 0.2500 | 20 | 28 |
| 5/16 | 0.3125 | 18 | 24 |
| 3/8 | 0.3750 | 16 | 24 |
| 7/16 | 0.4375 | 14 | 20 |
| 1/2 | 0.5000 | 13 | 20 |
| 9/16 | 0.5625 | 12 | 18 |
| 5/8 | 0.6250 | 11 | 18 |
| 3/4 | 0.7500 | 10 | 16 |
| 7/8 | 0.8750 | 9 | 14 |
| 1 | 1.0000 | 8 | 12 |
Metric
| Size | Coarse pitch | Fine pitch |
|---|---|---|
| M1.6 | 0.35 | - |
| M2 | 0.4 | - |
| M2.5 | 0.45 | - |
| M3 | 0.5 | - |
| M4 | 0.7 | - |
| M5 | 0.8 | - |
| M6 | 1.0 | - |
| M8 | 1.25 | 1.0 |
| M10 | 1.5 | 1.25 |
| M12 | 1.75 | 1.25 / 1.5 |
| M14 | 2.0 | 1.5 |
| M16 | 2.0 | 1.5 |
| M18 | 2.5 | 1.5 |
| M20 | 2.5 | 1.5 |
| M22 | 2.5 | 1.5 |
| M24 | 3.0 | 2.0 |
| M27 | 3.0 | 2.0 |
| M30 | 3.5 | 2.0 |
NPT pipe
| NPT | TPI | Pipe OD | Tap drill |
|---|---|---|---|
| 1/16 | 27 | .3125 | D |
| 1/8 | 27 | .405 | R |
| 1/4 | 18 | .540 | 7/16 |
| 3/8 | 18 | .675 | 37/64 |
| 1/2 | 14 | .840 | 23/32 |
| 3/4 | 14 | 1.050 | 59/64 |
| 1 | 11.5 | 1.315 | 1-5/32 |
| 1-1/4 | 11.5 | 1.660 | 1-1/2 |
| 1-1/2 | 11.5 | 1.900 | 1-23/32 |
| 2 | 11.5 | 2.375 | 2-3/16 |
Numbered screw major diameter = .060 + .013 × N. Pitch = 1 / TPI.
Printable PDF version - Thread Chart
Clean letter-size sheet for the toolbox or shop wall. Instant download, $3.49.
Clean letter-size sheet for the toolbox or shop wall. Instant download, $3.49.