Dimensions, drill sizes and wrench sizes for #12-32 UNEF.
Designation
#12-32 UNEF
Major (outside) diameter
5.486 mm · 0.216"
Pitch
0.794 mm · 32 TPI
Pitch diameter
4.971 mm · 0.1957"
Minor diameter (external)
4.513 mm · 0.1777"
Minor diameter (internal)
4.627 mm · 0.1822"
Recommended tap drill
#13 · 4.7 mm · ≈76% thread
Clearance hole
Close A · Normal D · Loose J - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
Close A · Normal D · Loose J - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
#12-32 UNEF in numbers
#12-32 UNEF is 0.2160 in across the crests with 32 threads per inch, a 0.794 mm pitch. The basic pitch diameter is 4.971 mm and the bolt's minor diameter 4.513 mm, so the thread is 0.486 mm deep on the bolt. Its tensile stress area is 0.027 in², 12% more than the coarser #12-24 UNC at the same diameter. The nearest metric size, M5 × 0.8, is 0.49 mm smaller across the crests and its pitch is 0.006 mm coarser, so the two do not interchange.
Tap drill by thread percentage
Hole = D − % × 0.0129904 × P, with D = 5.486 mm and P = 0.794 mm. A smaller hole leaves more thread; the recommended #13 drill above gives about 76%.
Tap-drill hole diameters for #12-32 UNEF at several thread percentages.
Thread
Hole (mm)
Hole (in)
Nearest drill
60%
4.87
0.1916
#11 (0.1910 in) gives 62%
65%
4.82
0.1896
#12 (0.1890 in) gives 67%
70%
4.76
0.1876
3/16" (0.1875 in) gives 70%
75%
4.71
0.1855
#13 (0.1850 in) gives 76%
Tightening torque estimate
SAE J429 tabulates grades from 1/4 in upwards, so no proof load or tightening torque is published for numbered sizes.
Put #12-32 UNEF on a job sheet
The bolt schedule collects the fasteners for one job onto a single sheet - tap drill, wrench size, grade and tightening torque on every line, taken straight from pages like this one. Free schedules hold 3 lines and are saved in this browser only.
For a #12-32 UNEF thread, drill the hole with a #13 tap drill (4.7 mm) before tapping. That produces roughly 76% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 5.486 mm and a pitch of 0.794 mm (32 TPI).
To pass a #12-32 UNEF bolt through a part rather than thread it, use a clearance hole: Close A · Normal D · Loose J - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice)..
All values come from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables. See the full reference.
Frequently asked questions
What drill size do I need to tap a #12-32 UNEF thread?
Drill #13 (4.7 mm) before tapping #12-32 UNEF. That leaves roughly 76% thread engagement, the usual target for a strong hole that still taps cleanly.
Is #12-32 UNEF a coarse or fine thread?
#12-32 UNEF is a Unified extra-fine (UNEF) thread at 32 threads per inch, used for thin-wall parts, short thread engagement and fine adjustment.
What size clearance hole does a #12-32 UNEF bolt need?
Close A · Normal D · Loose J - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice). A clearance hole lets the #12-32 UNEF bolt pass through the part instead of threading into it.
What is the pitch diameter of #12-32 UNEF?
The pitch diameter of #12-32 UNEF is 4.971 mm (0.1957"). It is the diameter where the thread ridge and groove are equally wide, and the reference dimension for checking thread fit.
Nearest standard metric sizes by major diameter. These are substitutes by size only - the thread forms are not interchangeable, so never run one into the other.