#8-36 UNF thread pitch and dimensions
The #8-36 UNF thread has 36 threads per inch, a pitch of 0.0278 in (0.71 mm), on a 0.164 in major diameter (ASME B1.1). Its basic pitch diameter is 0.1460 in and its basic minor diameter is 0.1339 in.
Need it made?
Need a part with #8-36 UNF threads machined? Post it free — local makers quote.
Got the machine? Sell your time on The Spool List. Join as a maker
| Dimension | Formula | inch | mm |
|---|---|---|---|
| Major diameter D | nominal | 0.1640 | 4.17 |
| Pitch P | 1 / TPI | 0.0278 | 0.71 |
| Pitch diameter E | D − 0.649519 / n | 0.1460 | 3.71 |
| Minor diameter (internal) | D − 1.082532 / n | 0.1339 | 3.4 |
| Thread height (basic) | 0.541266 / n | 0.0150 | 0.38 |
| Tensile stress area As | 0.7854 (D − 0.9743 / n)² | 0.0147 in² | 9.5 mm² |
| Thread | TPI | Pitch Ø E | Stress area As | Tap drill |
|---|---|---|---|---|
| #8-32 UNC | 32 | 0.1437 in | 0.0140 in² | #29 |
| #8-36 UNF (this page) | 36 | 0.1460 in | 0.0147 in² | #29 |
| Thread | TPI | Pitch (mm) | Minor Ø | Stress area As |
|---|---|---|---|---|
| #4-48 UNF | 48 | 0.53 | 0.0894 in | 0.0066 in² |
| #6-40 UNF | 40 | 0.64 | 0.1109 in | 0.0101 in² |
| #8-36 UNF (this page) | 36 | 0.71 | 0.1339 in | 0.0147 in² |
| #10-32 UNF | 32 | 0.79 | 0.1562 in | 0.0200 in² |
| 1/4-28 UNF | 28 | 0.91 | 0.2113 in | 0.0364 in² |
Practical notes
Unified threads are named diameter–TPI–series: #8-36 UNF is a #8 nominal diameter (number 8 screw, 0.164 in) with 36 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.
36 TPI is a pitch of 0.71 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 #8-36 UNF it is 0.0147 in².
FAQ
How many threads per inch is #8-36 UNF?
36 TPI, a pitch of 0.0278 in (0.71 mm), in the Unified fine series (ASME B1.1).
What is the minor diameter of #8-36 UNF?
The basic minor diameter of the internal thread is D − 1.082532/n = 0.1339 in (3.4 mm).
What is the tensile stress area of #8-36 UNF?
As = 0.7854 × (D − 0.9743/n)² = 0.0147 in² (9.5 mm²).
What tap drill does #8-36 UNF need?
The standard chart drill is #29, 0.1360 in (3.45 mm), about 78% thread.
What is the difference between #8-36 UNF and #8-32 UNC?
Same #8 diameter, different pitch: 36 TPI versus 32 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)
Find a maker
Post the job free — verified makers quote you.
Post a CNC machining job Open the Thread Pitch & Dimensions Chart calculator