#10-32 UNF thread pitch and dimensions
The #10-32 UNF thread has 32 threads per inch, a pitch of 0.0313 in (0.79 mm), on a 0.190 in major diameter (ASME B1.1). Its basic pitch diameter is 0.1697 in and its basic minor diameter is 0.1562 in.
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| Dimension | Formula | inch | mm |
|---|---|---|---|
| Major diameter D | nominal | 0.1900 | 4.83 |
| Pitch P | 1 / TPI | 0.0313 | 0.79 |
| Pitch diameter E | D − 0.649519 / n | 0.1697 | 4.31 |
| Minor diameter (internal) | D − 1.082532 / n | 0.1562 | 3.97 |
| Thread height (basic) | 0.541266 / n | 0.0169 | 0.43 |
| Tensile stress area As | 0.7854 (D − 0.9743 / n)² | 0.0200 in² | 12.9 mm² |
| Thread | TPI | Pitch Ø E | Stress area As | Tap drill |
|---|---|---|---|---|
| #10-24 UNC | 24 | 0.1629 in | 0.0175 in² | #25 |
| #10-32 UNF (this page) | 32 | 0.1697 in | 0.0200 in² | #21 |
| Thread | TPI | Pitch (mm) | Minor Ø | Stress area As |
|---|---|---|---|---|
| #6-40 UNF | 40 | 0.64 | 0.1109 in | 0.0101 in² |
| #8-36 UNF | 36 | 0.71 | 0.1339 in | 0.0147 in² |
| #10-32 UNF (this page) | 32 | 0.79 | 0.1562 in | 0.0200 in² |
| 1/4-28 UNF | 28 | 0.91 | 0.2113 in | 0.0364 in² |
| 5/16-24 UNF | 24 | 1.06 | 0.2674 in | 0.0581 in² |
Practical notes
Unified threads are named diameter–TPI–series: #10-32 UNF is a #10 nominal diameter (number 10 screw, 0.190 in) with 32 threads per inch in the fine series.
These are basic (zero-tolerance) dimensions. Most screws are made to class 2A and nuts to 2B (ASME B1.1), so measured sizes sit slightly below the basic values on the screw.
32 TPI is a pitch of 0.79 mm, which does not match a metric ISO pitch exactly; metric and Unified fasteners of similar size are not interchangeable.
Tensile stress area As is the area used for bolt strength (proof load = As × proof stress for the SAE J429 or ASTM grade). For #10-32 UNF it is 0.0200 in².
FAQ
How many threads per inch is #10-32 UNF?
32 TPI, a pitch of 0.0313 in (0.79 mm), in the Unified fine series (ASME B1.1).
What is the minor diameter of #10-32 UNF?
The basic minor diameter of the internal thread is D − 1.082532/n = 0.1562 in (3.97 mm).
What is the tensile stress area of #10-32 UNF?
As = 0.7854 × (D − 0.9743/n)² = 0.0200 in² (12.9 mm²).
What tap drill does #10-32 UNF need?
The standard chart drill is #21, 0.1590 in (4.04 mm), about 76% thread.
What is the difference between #10-32 UNF and #10-24 UNC?
Same #10 diameter, different pitch: 32 TPI versus 24 TPI. They are not interchangeable.
Sources: ASME B1.1 — Unified inch screw threads (UN and UNR thread form): basic dimensions, tensile stress area · ASME B18.2.1 — square, hex, heavy hex and askew head bolts and hex, heavy hex, hex flange screws (width across flats)
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