Date Updated:Apr. 27. 2026
Unified Coarse Screw Threads/Unified Fine Screw Threads
Unified Coarse Screw Threads/Unified Fine Screw Threads
Basic profile, formula and basic dimensions of unified coarse threads / fine threads
Unified Coarse Threads (UNC)
| Nominal Designation | Internal Thread | |||
|---|---|---|---|---|
| Major Diameter D |
Pitch Diameter D2 |
Minor Diameter D1 |
||
| 1 | 2 | External Thread | ||
| Major Diameter d |
Pitch Diameter d2 |
Minor Diameter d1 |
||
No. 2-56 UNC |
No. 1 - 64 UNC No. 3 - 48 UNC |
1.854 2.184 2.515 |
1.598 1.890 2.172 |
1.425 1.694 1.941 |
| No. 4-40 UNC No. 5-40 UNC No. 6-32 UNC |
2.845 3.175 3.505 |
2.433 2.764 2.990 |
2.156 2.487 2.647 |
|
| No. 8-32 UNC No. 10-24 UNC |
No.12 - 24 UNC |
4.166 4.826 5.486 |
3.650 4.138 4.798 |
3.307 3.680 4.341 |
| 1／4 -20 UNC 5／16 -18 UNC 3／8 -16 UNC |
6.350 7.938 9.525 |
5.524 7.021 8.494 |
4.976 6.411 7.805 |
|
| 7／16 -14 UNC 1／2 -13 UNC |
11.112 12.700 |
9.934 11.430 |
9.149 10.584 |
|
＊Prioritize Field 1, and choose Field 2 as needed.
Unified Fine Threads (UNF)
| No. 0-80 UNF No. 2-64 UNF |
No. 1 - 72 UN |
1.524 1.854 2.184 |
1.318 1.626 1.928 |
1.181 1.473 1.755 |
|---|---|---|---|---|
No. 4-48 UNF No. 5-44 UNF |
No. 3 - 56 UNF |
2.515 2.845 3.175 |
2.220 2.502 2.799 |
2.024 2.271 2.550 |
| No. 6-40 UNF No. 8-36 UNF No. 10-32 UNF |
3.505 4.166 4.826 |
3.094 3.708 4.310 |
2.817 3.401 3.967 |
|
1／4 -28 UNF 5／16 -24 UNF |
No.12 - 28 UNF |
5.486 6.350 7.938 |
4.897 5.761 7.249 |
4.503 5.367 6.792 |
| 3／8 -24 UNF 7／16 -20 UNF 1／2 -20 UNF |
9.525 11.112 12.700 |
8.837 10.287 11.874 |
8.379 9.738 11.326 |
＊Prioritize Field 1, and choose Field 2 as needed.
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