Reference
UNC/UNF Screw Thread Dimensions
The standard UNC (coarse) and UNF (fine) unified inch-screw-thread sizes, preserved from werktuigbouw.nl’s UNC/UNF calculators.
Threads per inch (N) and major diameter (d) are the two figures the calculators need; pitch (P = 1/N) and the metric-equivalent diameter are given for convenience.
Used by the UNC fastener in tension calculator and the other UNC/UNF fastener calculators.
UNC — coarse thread
| Designation | Major diameter, d (in) | Major diameter, d (mm) | Threads per inch, N | Pitch, P = 1/N (in) |
|---|---|---|---|---|
| 1-64 UNC | 0.073 | 1.85 | 64 | 0.0156 |
| 2-56 UNC | 0.086 | 2.18 | 56 | 0.0179 |
| 3-48 UNC | 0.099 | 2.51 | 48 | 0.0208 |
| 4-40 UNC | 0.112 | 2.84 | 40 | 0.0250 |
| 5-40 UNC | 0.125 | 3.17 | 40 | 0.0250 |
| 6-32 UNC | 0.138 | 3.51 | 32 | 0.0313 |
| 8-32 UNC | 0.164 | 4.17 | 32 | 0.0313 |
| 10-24 UNC | 0.19 | 4.83 | 24 | 0.0417 |
| 12-24 UNC | 0.216 | 5.49 | 24 | 0.0417 |
| 1/4-20 UNC | 0.25 | 6.35 | 20 | 0.0500 |
| 5/16-18 UNC | 0.3125 | 7.94 | 18 | 0.0556 |
| 3/8-16 UNC | 0.375 | 9.52 | 16 | 0.0625 |
| 7/16-14 UNC | 0.4375 | 11.11 | 14 | 0.0714 |
| 1/2-13 UNC | 0.5 | 12.70 | 13 | 0.0769 |
| 9/16-12 UNC | 0.5625 | 14.29 | 12 | 0.0833 |
| 5/8-11 UNC | 0.625 | 15.88 | 11 | 0.0909 |
| 3/4-10 UNC | 0.75 | 19.05 | 10 | 0.1000 |
| 7/8-9 UNC | 0.875 | 22.22 | 9 | 0.1111 |
| 1-8 UNC | 1 | 25.40 | 8 | 0.1250 |
| 1 1/8-7 UNC | 1.125 | 28.57 | 7 | 0.1429 |
| 1 1/4-7 UNC | 1.25 | 31.75 | 7 | 0.1429 |
| 1 3/8-6 UNC | 1.375 | 34.92 | 6 | 0.1667 |
| 1 1/2-6 UNC | 1.5 | 38.10 | 6 | 0.1667 |
| 1 3/4-5 UNC | 1.75 | 44.45 | 5 | 0.2000 |
| 2-4.5 UNC | 2 | 50.80 | 4.5 | 0.2222 |
| 2 1/4-4.5 UNC | 2.25 | 57.15 | 4.5 | 0.2222 |
| 2 1/2-4 UNC | 2.5 | 63.50 | 4 | 0.2500 |
| 2 3/4-4 UNC | 2.75 | 69.85 | 4 | 0.2500 |
| 3-4 UNC | 3 | 76.20 | 4 | 0.2500 |
| 3 1/4-4 UNC | 3.25 | 82.55 | 4 | 0.2500 |
| 3 1/2-4 UNC | 3.5 | 88.90 | 4 | 0.2500 |
| 3 3/4-4 UNC | 3.75 | 95.25 | 4 | 0.2500 |
| 4-4 UNC | 4 | 101.60 | 4 | 0.2500 |
UNF — fine thread
| Designation | Major diameter, d (in) | Major diameter, d (mm) | Threads per inch, N | Pitch, P = 1/N (in) |
|---|---|---|---|---|
| 0-80 UNF | 0.06 | 1.52 | 80 | 0.0125 |
| 1-72 UNF | 0.073 | 1.85 | 72 | 0.0139 |
| 2-64 UNF | 0.086 | 2.18 | 64 | 0.0156 |
| 3-56 UNF | 0.099 | 2.51 | 56 | 0.0179 |
| 4-48 UNF | 0.112 | 2.84 | 48 | 0.0208 |
| 5-44 UNF | 0.125 | 3.17 | 44 | 0.0227 |
| 6-40 UNF | 0.138 | 3.51 | 40 | 0.0250 |
| 8-36 UNF | 0.164 | 4.17 | 36 | 0.0278 |
| 10-32 UNF | 0.19 | 4.83 | 32 | 0.0313 |
| 12-28 UNF | 0.216 | 5.49 | 28 | 0.0357 |
| 1/4-28 UNF | 0.25 | 6.35 | 28 | 0.0357 |
| 5/16-24 UNF | 0.3125 | 7.94 | 24 | 0.0417 |
| 3/8-24 UNF | 0.375 | 9.52 | 24 | 0.0417 |
| 7/16-20 UNF | 0.4375 | 11.11 | 20 | 0.0500 |
| 1/2-20 UNF | 0.5 | 12.70 | 20 | 0.0500 |
| 9/16-18 UNF | 0.5625 | 14.29 | 18 | 0.0556 |
| 5/8-18 UNF | 0.625 | 15.88 | 18 | 0.0556 |
| 3/4-16 UNF | 0.75 | 19.05 | 16 | 0.0625 |
| 7/8-14 UNF | 0.875 | 22.22 | 14 | 0.0714 |
| 1-12 UNF | 1 | 25.40 | 12 | 0.0833 |
| 1 1/8-12 UNF | 1.125 | 28.57 | 12 | 0.0833 |
| 1 1/4-12 UNF | 1.25 | 31.75 | 12 | 0.0833 |
| 1 3/8-12 UNF | 1.375 | 34.92 | 12 | 0.0833 |
| 1 1/2-12 UNF | 1.5 | 38.10 | 12 | 0.0833 |
Source: werktuigbouw.nl’s unc_1.htm/unc_2.htm and unf_1.htm/unf_2.htm calculator forms, preserved verbatim.