UNC brass hex nut (ASME B18.2.2) — engineering drawing (Brassland).
Specification
| Standard | ASME B18.2.2 (nuts for general applications, inch series) |
| Type | Finished hex nuts and hex jam nuts |
| Thread | 1/4-20 to 3/4-10 UNC; UNF pitches (e.g. 1/4-28, 5/16-24, 3/8-24, 1/2-20) on the same nut body |
| Material | C36000 free-machining brass (UNS) — EN twin CW614N (CuZn39Pb3); lead-free C69300 / CW724R on request |
| Certificate | EN 10204 3.1 per shipment; 3.2 on request |
Datasheet — hex nuts to ASME B18.2.2
| Nominal size | Width A/F F basic | F max | F min | Corners G max | G min | Thickness H basic | H max | H min |
|---|---|---|---|---|---|---|---|---|
| 1/4 | 7/16 (0.4375) | 0.438 | 0.428 | 0.505 | 0.488 | 7/32 (0.219) | 0.226 | 0.212 |
| 5/16 | 1/2 (0.500) | 0.500 | 0.489 | 0.577 | 0.557 | 17/64 (0.266) | 0.273 | 0.258 |
| 3/8 | 9/16 (0.5625) | 0.562 | 0.551 | 0.650 | 0.628 | 21/64 (0.328) | 0.337 | 0.320 |
| 7/16 | 11/16 (0.6875) | 0.688 | 0.675 | 0.794 | 0.768 | 3/8 (0.375) | 0.385 | 0.365 |
| 1/2 | 3/4 (0.750) | 0.750 | 0.736 | 0.866 | 0.840 | 7/16 (0.438) | 0.448 | 0.427 |
| 5/8 | 15/16 (0.9375) | 0.938 | 0.922 | 1.083 | 1.051 | 35/64 (0.547) | 0.559 | 0.535 |
| 3/4 | 1-1/8 (1.125) | 1.125 | 1.088 | 1.299 | 1.240 | 41/64 (0.641) | 0.665 | 0.617 |
Dimensions in inches to ASME B18.2.2 (finished hex nuts). Thread pitch does not change the nut body — UNC and UNF nuts of the same nominal size share identical dimensions. Sizes above 3/4 in. machined to your drawing. Full dimension chart: ASME B18.2.2 hex & jam nut dimension chart →
Datasheet — hex jam nuts to ASME B18.2.2
| Nominal size | Jam thickness H1 basic | H1 max | H1 min |
|---|---|---|---|
| 1/4 | 5/32 (0.156) | 0.163 | 0.150 |
| 5/16 | 3/16 (0.188) | 0.195 | 0.180 |
| 3/8 | 7/32 (0.219) | 0.227 | 0.210 |
| 7/16 | 1/4 (0.250) | 0.260 | 0.240 |
| 1/2 | 5/16 (0.312) | 0.323 | 0.302 |
| 5/8 | 3/8 (0.375) | 0.387 | 0.363 |
| 3/4 | 27/64 (0.422) | 0.446 | 0.398 |
Jam nuts use the same width across flats and across corners as the hex nuts above — only the thickness differs. Dimensions in inches to ASME B18.2.2.
Scope note — small sizes
ASME B18.2.2 hex nuts start at 1/4 in. nominal size. Smaller inch nuts — #4-40, #6-32, #8-32, #10-24 and #10-32 — are machine screw nuts dimensioned to ASME B18.6.3, a separate (thinner) series: see our UNC brass machine screw nuts page. The metric equivalent of this page is the DIN 934 / ISO 4032 brass hex nut.
Applications
UNC and UNF brass hex nuts are used across US-market plumbing and fitting assemblies, electrical and grounding hardware, panel and enclosure fixings, instrumentation, and marine and decorative hardware. All parts are made to order: threads, platings (tin, nickel), across-flats variants and certifications follow your specification. Free-machining brass gives clean threads and a corrosion-resistant, non-magnetic nut.
Imperial & UNC range
Related pages
All DIN / ISO / ANSI nut types.
View →Metric equivalentThe metric twin — ISO 4032 hex nut.
View →Product#0–3/8 small hex nuts, ASME B18.6.3.
View →MaterialUS free-machining brass datasheet.
View →MaterialSilicon brass for potable / RoHS work.
View →GuideUNC / UNF, metric and BSP reference.
View →Quote in 24 hours.
Give the standard, thread, finish and quantity. We machine inch-series brass parts in Jamnagar, India, and export to 40+ countries.
Sources & references
Dimension tables above follow ASME B18.2.2 and were cross-checked against three concordant published references, including the Engineers Edge ANSI/ASME B18.2.2 hex and jam nut tables and two independent fastener-industry dimension charts (verified July 2026). The governing document is ASME B18.2.2.
Frequently asked questions
No. ASME B18.2.2 hex nuts start at 1/4 in. nominal size. Smaller inch hex nuts — #4-40, #6-32, #8-32, #10-24 and #10-32 — are machine screw nuts dimensioned to ASME B18.6.3, a separate and slightly thinner series. Brassland machines both.
No. Thread pitch does not change the nut body: a 1/4-20 (UNC) and a 1/4-28 (UNF) hex nut share identical width across flats and thickness, and the same holds for the 5/16, 3/8 and 1/2 in. coarse/fine pairs. Only the internal thread differs.
A 3/4 in. wrench — ASME B18.2.2 gives the 1/2 in. hex nut a basic width across flats of 3/4 in. (0.750 in.). The 1/2 in. jam nut uses the same across-flats with a thinner 5/16 in. body.
Same across-flats, thinner body: at 1/2 in. the finished hex nut is 7/16 in. thick while the jam nut is 5/16 in. Jam nuts are tightened against a full nut as a locking nut, or used where axial space is tight.
C36000 free-machining brass — the standard US screw-machine alloy, the EN twin of CW614N (CuZn39Pb3). Lead-free alloys such as C69300 silicon brass are machined on request for potable-water and RoHS-sensitive work.