Socket Head Bolt Size Chart & Socket Head Bolt Sizes | Factory
⚠️ Why Most Buyers Get Socket Head Bolt Sizes Wrong
Sourcing the right socket head bolt sizes isn’t just about matching threads — it affects your entire assembly line, warranty costs, and delivery schedule.
Mismatched Threads
M6 vs 1/4″ — one wrong call and your entire batch fails QC. 34% of procurement delays come from incorrect socket head bolt size chart reference.
Hidden Cost Overruns
Low‑grade bolts (grade 4.8) fail under shear stress, causing rework costs up to 18% of project value. You need verified grade 8.8–12.9 data upfront.
High Shipping & Lead Time
Sourcing from multiple suppliers inflates freight cost by ~22%. A single factory‑direct source for all socket head bolt sizes cuts logistics complexity.
Missing Compliance Docs
Without ISO, CE, or RoHS certificates, your customs clearance stalls. 67% of buyers require full certification before PO approval.
👉 You need a socket head bolt size chart that’s accurate, certified, and factory‑backed.
✅ Boen Fastener – Complete Socket Head Bolt Solution
We provide the most comprehensive socket head bolt sizes range from M3 to M48, inch sizes 1/4″ to 2″, in grades 8.8, 10.9, and 12.9. Every batch is traceable and tested.
Factory Direct
Eliminate middle‑man markup. Our price is 30–40% lower than distributor lists.
Full Size Range
M3–M48, 1/4″–2″, UNC/UNF/ISO. Custom lengths available.
Grade 8.8–12.9
Heat‑treated, hardness tested, proof load verified.
Fast Lead Time
15–25 days for standard sizes; express available.
📊 Socket Head Bolt Size Chart – Metric & Inch
| Size | Thread Pitch (mm / TPI) | Head Diameter (mm) | Head Height (mm) | Grade | Proof Load (kN) |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 3.0 | 8.8 | 2.8 |
| M4 | 0.7 | 7.0 | 4.0 | 10.9 | 5.2 |
| M5 | 0.8 | 8.5 | 5.0 | 10.9 | 8.5 |
| M6 | 1.0 | 10.0 | 6.0 | 12.9 | 12.1 |
| M8 | 1.25 | 13.0 | 8.0 | 12.9 | 22.0 |
| M10 | 1.5 | 16.0 | 10.0 | 12.9 | 35.0 |
| M12 | 1.75 | 18.0 | 12.0 | 12.9 | 50.5 |
| M16 | 2.0 | 24.0 | 16.0 | 12.9 | 94.0 |
| 1/4″ | 20 UNF | 11.1 | 6.3 | Grade 8 | 14.2 |
| 3/8″ | 16 UNC | 16.0 | 9.5 | Grade 8 | 34.0 |
📌 Full socket head bolt size chart available for download with your quote. Custom thread lengths & coating options (Dacromet, zinc‑nickel, black oxide) also available.
🏗️ Real‑World Applications
Agricultural Machinery
Grade 10.9 socket head bolts used in harvester sub‑assemblies — zero failure in 3‑year field test.
Automotive Chassis
M8×1.25 socket head cap screws in grade 12.9, black oxide finish, passed 200h salt spray.
Structural Steel
M16 socket head bolts for crane rail clamps — proof load 94kN, 100% magnetic particle inspected.
❓ FAQ – Socket Head Bolt Sizes & Sourcing
Quick answers to the most common questions from procurement and engineering teams.
🔹 What is the difference between socket head bolt sizes and regular hex bolts?
Socket head cap screws have a cylindrical head with a hex socket drive, allowing higher torque and a smaller head profile. They are typically used in tight spaces and require a socket head bolt size chart to match the correct drive size (e.g., hex key) to the bolt diameter.
🔹 Where can I find a reliable socket head bolt size chart with metric and inch units?
You’re looking at it! Our table above covers M3–M16 and 1/4″–3/8″. For the full socket head bolt size chart (up to M48, 2″), request our technical datasheet — it includes thread pitch, head dimensions, proof loads, and recommended tightening torque.
🔹 What grades of socket head bolts do you offer? Can I get grade 12.9?
Yes — we stock grades 8.8, 10.9, and 12.9 in metric, and Grade 5, Grade 8, and B7 in inch. Grade 12.9 is heat‑treated and proof‑load tested. We also offer custom hardness for specialized applications.
🔹 What is the minimum order quantity (MOQ) for socket head bolts?
For standard sizes (M3–M20, 1/4″–3/4″) our MOQ is 500 pcs per size. For larger sizes or custom lengths, MOQ is 200 pcs. We also offer sample packs (50 pcs) for qualification.
🔹 Do you provide certificates of conformity and material test reports?
Absolutely. Every shipment includes ISO 9001, CE, RoHS, and a mill test certificate (MTC). Third‑party testing (SGS, BV) is available at cost.
🔹 How long does shipping take to the USA or Europe?
By sea: 25–35 days to US West Coast / Rotterdam. By air: 5–7 days. We handle all customs documentation. Express (DHL/FedEx) for samples: 3–5 days.
🔹 Can I get custom lengths or coatings like zinc‑nickel or Dacromet?
Yes. Custom lengths (any increment) and coatings: zinc‑nickel, Dacromet, Geomet, black oxide, hot‑dip galvanized. Lead time adds 5–7 days. Just send your spec.
⭐ What Our Customers Say
“The socket head bolt sizes we ordered matched the chart perfectly. No surprises, no rejects. That’s rare.”
— Marco Rossi, Engineering Manager, Italy
“Boen’s factory‑direct pricing and fast delivery helped us meet a tight deadline. 10/10 service.”
— Lisa Park, Purchasing Manager, South Korea
“We use Boen for all M12 socket head bolts. Consistent quality, correct paperwork every time.”
— David Chen, VP Operations, Taiwan
Li Wei is the head of product quality at Handan Boen Fastener. He has overseen over 1,200 export shipments and regularly consults on socket head bolt size chart standardization for OEMs across Europe and North America.
🚀 Get Your Custom Socket Head Bolt Quote Today
Free sample pack · 24h quote response · Full certificate package · Factory‑direct pricing
📧 shuan@fastenboen.com · mary@fastenboen.com · grace@fastenboen.com · stella@fastenboen.com
🔒 Risk‑free: free samples available · 30‑day quality guarantee
🏭 Factory Strength & Trust Signals
“The socket head bolt size chart from Boen saved us 3 weeks of cross‑referencing. Grade 12.9 M10 bolts arrived with full test reports — exactly as spec’d.”
Procurement Lead, Müller AG
“We switched to Boen for M6 socket head bolts — 32% cost saving vs our previous distributor. Lead time dropped from 42 to 18 days.”
Operations Manager, Tectra Industries
“ISO 9001 and CE docs came with the shipment. Customs clearance was seamless. We’ve placed 4 repeat orders this year.”
Supply Chain Manager, Westlink Corp.