ASME B18.2.2 Finished Hex Nuts
Finished hex nuts per ANSI/ASME B18.2.2 — the standard-pattern hex nut of the inch series, 1/4" through 2-1/2" nominal size, machined (rather than hot-forged) on both faces. Grade 2, 5 and 8 steel, 18-8 and 316 stainless, plain or hot-dip galvanized.
Last updated: 2026-11
Specifications
The finished hex nut is the everyday nut of the inch series: a hexagon driven by a standard wrench — width across flats is one and a half times the nominal thread size — with a section about seven-eighths of the diameter deep, and both faces machined to a clean bearing surface (the "finished" trait that separates it from the hot-forged unfinished pattern). The collected dimension table runs from 1/4" up past the 2-1/2" step of the common series, tabulating width across flats, width across corners and thickness at basic, max and min for every size. Strength is selected by grade: Grade 2 low-carbon steel for ordinary assemblies, Grade 5 for higher clamp loads, Grade 8 for the top of the range, and 18-8 or 316 stainless where corrosion decides. When the joint needs more bearing surface and section than this standard pattern gives, that is the heavy hex nut's job — the same thread size steps up to a wider, thicker body.
| Standard | ANSI/ASME B18.2.2 — finished hex nuts, inch series |
|---|---|
| Size range | 1/4" through 2-1/2" nominal thread size (collected chart continues to 3") |
| Dimensions at 1/2" | Width across flats 3/4" basic (.736–.750 in); width across corners .840–.866 in; thickness 7/16" basic (.427–.448 in) |
| Pattern proportions | Width across flats = 1-1/2 × D; thickness ≈ 7/8 × D (D = nominal size), per the collected pattern description |
| Series highlights (WAF basic, in) | 1/4 7/16 · 3/8 9/16 · 1/2 3/4 · 3/4 1-1/8 · 1 1-1/2 · 1-1/2 2-1/4 · 2 3 · 2-1/2 3-3/4 |
| Grade 2 | Proof load 90,000 psi coarse / 80,000 psi fine (Rockwell B68–32); for use with low-carbon bolts of 74,000 psi min tensile or less |
| Grade 5 | Proof load 120,000 psi coarse / 109,000 psi fine over 1/4"–1"; AISI 1008–1026 |
| Grade 8 | Proof load 150,000 psi over 1/4"–1-1/2"; AISI 1021–1045 |
| Stainless | 18-8 (303, 303s, 304, XM7) and 316; proof load 100,000 psi coarse / 85,000 psi fine; 316 adds 2–3% molybdenum for corrosion and elevated-temperature strength |
| Hot-dip galvanized | Low-carbon steel with a galvanized zinc coating; proof load 68,000 psi coarse / 60,000 psi fine |
| Vs heavy hex | The heavy hex pattern is wider and thicker at the same thread — 1/2" heavy hex spans 7/8" across flats against 3/4" here |
| Typical applications | General-purpose inch-series clamping; Grade 2 finished hex nuts are the most versatile and commonly used nut design |
| Nominal Size | Basic Major Dia. of Thread | F — Across Flats (min) | F (max) | G — Across Corners (min) | G (max) | H — Hex Nut Thickness (min) | H (max) | H1 — Jam Nut Thickness (min) | H1 (max) |
|---|---|---|---|---|---|---|---|---|---|
| 1/4 | 0.2500 | 0.428 | 0.438 | 0.488 | 0.505 | 0.212 | 0.226 | 0.150 | 0.163 |
| 5/16 | 0.3125 | 0.489 | 0.500 | 0.557 | 0.577 | 0.258 | 0.273 | 0.180 | 0.195 |
| 3/8 | 0.3750 | 0.551 | 0.563 | 0.628 | 0.650 | 0.320 | 0.337 | 0.210 | 0.227 |
| 7/16 | 0.4375 | 0.675 | 0.688 | 0.768 | 0.794 | 0.365 | 0.385 | 0.240 | 0.260 |
| 1/2 | 0.5000 | 0.736 | 0.750 | 0.840 | 0.866 | 0.427 | 0.448 | 0.302 | 0.323 |
| 9/16 | 0.5625 | 0.861 | 0.875 | 0.982 | 1.010 | 0.473 | 0.496 | 0.301 | 0.324 |
| 5/8 | 0.6250 | 0.922 | 0.938 | 1.051 | 1.083 | 0.535 | 0.559 | 0.363 | 0.387 |
| 3/4 | 0.7500 | 1.088 | 1.125 | 1.240 | 1.299 | 0.617 | 0.665 | 0.398 | 0.446 |
| 7/8 | 0.8750 | 1.269 | 1.312 | 1.447 | 1.516 | 0.724 | 0.776 | 0.458 | 0.510 |
| 1 | 1.0000 | 1.450 | 1.500 | 1.653 | 1.732 | 0.831 | 0.887 | 0.519 | 0.575 |
| 1 1/8 | 1.1250 | 1.631 | 1.688 | 1.859 | 1.949 | 0.939 | 0.999 | 0.579 | 0.639 |
| 1 1/4 | 1.2500 | 1.812 | 1.875 | 2.066 | 2.165 | 1.030 | 1.094 | 0.687 | 0.751 |
| 1 3/8 | 1.3750 | 1.994 | 2.062 | 2.273 | 2.382 | 1.138 | 1.206 | 0.747 | 0.815 |
| 1 1/2 | 1.5000 | 2.175 | 2.250 | 2.480 | 2.598 | 1.245 | 1.317 | 0.808 | 0.880 |
| 1 5/8 | 1.6250 | 2.35 | 2.43 | 2.679 | 2.805 | 1.364 | 1.416 | 0.868 | 0.944 |
| 1 3/4 | 1.7500 | 2.538 | 2.625 | 2.893 | 3.031 | 1.460 | 1.540 | 0.929 | 1.009 |
| 1 7/8 | 1.8750 | 2.722 | 2.813 | 3.103 | 3.247 | 1.567 | 1.651 | 0.989 | 1.073 |
| 2 | 2.0000 | 2.900 | 3.000 | 3.306 | 3.464 | 1.675 | 1.763 | 1.050 | 1.138 |
| 2 1/4 | 2.2500 | 3.263 | 3.375 | 3.719 | 3.897 | 1.890 | 1.986 | 1.155 | 1.267 |
| 2 1/2 | 2.5000 | 3.625 | 3.750 | 4.133 | 4.330 | 2.105 | 2.209 | 1.401 | 1.427 |
| 2 3/4 | 2.7500 | 3.988 | 4.125 | 4.546 | 4.763 | 2.319 | 2.431 | 1.522 | 1.556 |
| 3 | 3.0000 | 4.350 | 4.500 | 4.959 | 5.196 | 2.534 | 2.654 | 1.643 | 1.685 |
| 3 1/4 | 3.2500 | 4.713 | 4.875 | 5.373 | 5.629 | 2.749 | 2.877 | 1.748 | 1.814 |
| 3 1/2 | 3.5000 | 5.075 | 5.250 | 5.786 | 6.062 | 2.964 | 3.100 | 1.870 | 1.943 |
| 3 3/4 | 3.7500 | 5.438 | 5.625 | 6.199 | 6.495 | 3.178 | 3.322 | 1.990 | 2.072 |
| 4 | 4.0000 | 5.800 | 6.000 | 6.612 | 6.928 | 3.393 | 3.545 | 2.112 | 2.201 |
Materials
- Low-carbon steel (Grade 2)
- Steel (Grade 5)
- Alloy steel (Grade 8)
- Stainless steel 18-8
- Stainless steel 316
- Hot-dip galvanized steel
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASME B18.2.2 Finished Hex Nuts) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Finished hex nut or heavy hex nut — which does my inch bolt need?
Both are ASME B18.2.2 patterns and both fit the same thread; they differ in body. At 1/2" the finished nut spans 3/4" across flats at 7/16" basic thickness, while the heavy hex runs 7/8" and 31/64" — more bearing surface and a deeper section for higher clamp loads. General machinery and assembly work on standard bolts takes the finished nut; structural and heavy-duty joints (A325/A490 bolting) call for the heavy pattern. Match the nut grade to the bolt strength and the wrench to the width across flats, and the two are otherwise interchangeable in handling.
What do Grade 2, Grade 5 and Grade 8 mean on an inch hex nut?
They are SAE-style strength steps for inch-series nuts, read as proof-load ratings. Grade 2 is low-carbon steel (90,000 psi coarse-thread proof load) for ordinary bolts; Grade 5 steps up to medium-carbon steel at 120,000 psi over 1/4"–1"; Grade 8 is alloy steel at 150,000 psi through 1-1/2". Pick the nut grade to at least match the bolt's strength class so the joint fails by bolt fracture, not thread stripping — and note hot-dip galvanized nuts carry reduced proof loads (68,000 psi coarse) because of the coating thickness.
What is the MOQ and lead time for this nut type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common diameters in this nut type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this nut type state?
State the standard designation (ANSI/ASME B18.2.2 finished hex), nominal thread size and threads-per-inch series, nut grade (Grade 2, 5 or 8, or 18-8 / 316 stainless), finish (plain, zinc-plated, or hot-dip galvanized where the reduced proof load is acceptable), any required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support