ANSI Inch Thread Stress and Shear Areas
Tensile stress area and bolt/nut thread strip area per inch of engagement for UNC/UNF/UN inch threads #0.1900-24 through 4.0000-8 UN, split by 2A/2B and 3A/3B class of fit — the inch-side companion to the metric stress-area table.
Last updated: 2026-11
Specifications
Thread shear-strip calculations for inch threads need the same two numbers the metric side uses — tensile stress area for the bolt strength check, thread strip area per inch of engagement for the stripping check — and the collected table carries both across the full UNC/UNF/UN ladder from 0.1900-24 to 4.0000-8 UN. The stress-area column shows the class-of-fit split: 3A/3B areas run slightly larger than 2A/2B (0.2500-20 UNC: 0.0318 vs 0.0318/0.0318 — the split is on the strip columns where it matters, bolt side 0.092 vs 0.096 in2/in at 2B/3B). Strip area grows linearly with engagement by definition (Le + 1 diameter on the bolt side, Le = diameter on the nut side), so the per-inch figures compare materials and classes directly: the nut strip area (0.135-0.141 in2/in at 1/4) always exceeds the bolt strip (0.092-0.096), which is why bolts strip before nuts and why the nut height rule of thumb exists. Source print defects carried verbatim: the 0.3750-16 row prints "UCN", the 0.4375-14 and 0.5000-13 rows print "UFC", and the 0.4375-14 stress area prints 0.0163 — out of family by a factor of five (its strip columns read ~0.30/0.43, in line with neighbours), flagged and quoted per RFQ rather than silently corrected.
| Series / scope | UNC/UNF/UN inch threads, 0.1900-24 UNC to 4.0000-8 UN, classes 2A/2B and 3A/3B — tensile stress area (sq in) and thread strip areas per the collected table |
|---|---|
| Tensile stress area | 2A/3A pairs: 0.0175/0.0200 at #0.1900 (UNC/UNF), 0.0318/0.0364 at 1/4, 0.0775/0.0878 at 3/8, 0.1419/0.1599 at 1/2, 3.56 at 2.2500-8 UN, 11.81 in2 at 4.0000-8 UN |
| Bolt thread strip area | Per inch of engagement (Le + 1 dia.), 2B/3B: 0.053/0.055 in2 at #0.1900-32 UNF, 0.092/0.096 (UNC) and 0.093/0.101 (UNF) at 1/4, 0.389/0.427 (UNC) at 1/2 — scales linearly with Le |
| Nut thread strip area | Per inch of engagement (Le = dia.), 2B/3B: 0.076/0.080 at #0.1900-24, 0.135/0.141 at 1/4-20, 0.562/0.581 at 1/2-13, 20.88/21.59 in2 at 3.0000-8 UN |
| Verbatim defects (flagged) | Row labels print "UCN" (0.3750-16) and "UFC" (0.4375-14, 0.5000-13); the 0.4375-14 stress area prints 0.0163 — inconsistent with its own strip columns and neighbours; carried verbatim, values per RFQ |
| Not tabulated | Stress areas by load basis (SAE vs ASME formulas), fine-pitch constant-pitch series beyond the UN 8-tni ladder printed, left-hand threads — per RFQ |
Materials
- Stress and strip areas are thread geometry, independent of material — but the stripping check that consumes them is not: strip strength depends on the softer of the mating materials (an aluminum nut against a steel bolt strips at the nut regardless of the bolt margin). Pair the area columns with the mating materials' shear strengths and the required engagement length; quote any thread outside the printed ladder per RFQ
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 (ANSI Inch Thread Stress and Shear Areas) 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
When do I need the strip-area columns rather than just the tensile stress area?
Whenever the joint fails by thread stripping instead of bolt fracture — soft nuts or housings, short engagement, large bolts on thin castings. The tensile stress area sizes the bolt; the strip areas size the engagement. Because the table prints area per inch of engagement, the stripping check is a one-step: required engagement = (load / (strip area per inch x shear strength of the weaker material)). The collected geometry shows the bolt side strips before the nut (0.092-0.096 vs 0.135-0.141 in2/in at 1/4), which is why the standard nut-height convention protects the bolt thread, and why a Class 3B fit buys a little more strip area (0.096 vs 0.092) at the cost of assembly ease. For dissimilar-material joints the same columns decide how much extra engagement buys back a soft housing.
What are the "UCN"/"UFC" labels and the 0.0163 figure in the table?
Source print defects, carried verbatim. The three rows labelled UCN/UFC are geometrically UNC/UNF series threads — the pitches, areas and strip columns line up with the standard series — so the labels are spelling errors on the collected page, not a fifth thread series. The 0.4375-14 stress area is a different kind of defect: 0.0163 in2 is roughly a fifth of what its own strip columns and the neighbouring ladder (0.0775 at 3/8, 0.1419 at 1/2) imply; the true figure is near 0.086 in2 but the collected source prints 0.0163, and this page does not silently correct numbers. Use the row's strip columns as printed and confirm the stress area per RFQ against the current ASME B1.1 before it feeds a calculation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
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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