Fastener Load Calculator – Calculate Fastener Capacity

Calculate the load capacity of fasteners including tensile and shear strength with safety factors.

Diameter (mm)

Tensile Strength (MPa)

Safety Factor

How to Calculate Fastener Load Capacity

Enter Fastener Diameter

Input the diameter of your bolt or fastener in millimeters.

Specify Material Strength

Enter the tensile strength of the fastener material in MPa.

View Load Capacities

Get ultimate load, allowable tensile load, and shear load capacity with safety factors.

Key Features of Fastener Load Calculator

✓Ultimate & Allowable Load

Calculate both the failure load and safe working load with configurable safety factors.

✓Shear Strength Calculation

Automatically computes shear capacity (typically 60% of tensile strength).

✓Configurable Safety Factor

Adjust safety factor based on application requirements (default: 2.0).

✓Metric Units Support

Uses standard metric units (mm, MPa, kN) for engineering calculations.

✓Quick Reference Values

Includes common fastener grades and their typical tensile strengths.

Fastener Load Formulas

Area = π × (d/2)²

Ultimate Load = Area × Tensile Strength

Allowable Load = Ultimate Load / Safety Factor

Shear Load ≈ Allowable Load × 0.6

Common Fastener Grades:

• Grade 2 (Steel): 420 MPa
• Grade 5 (Steel): 830 MPa
• Grade 8 (Steel): 1040 MPa
• A2 Stainless: 500 MPa
• A4 Stainless: 600 MPa

Example: M10 Grade 8.8 Bolt

• Diameter: 10 mm
• Tensile Strength: 800 MPa
• Ultimate Load: ~62.8 kN
• Allowable (SF=2): ~31.4 kN

Frequently Asked Questions About Fastener Loads

What is the difference between ultimate and allowable load?

Ultimate load is the force at which the fastener fails. Allowable load is the safe working load after applying a safety factor (typically 2-4x reduction).

What safety factor should I use?

Common safety factors are 2.0 for general applications, 3.0-4.0 for critical structural connections, and higher for dynamic or fatigue loading conditions.

Why is shear strength lower than tensile strength?

Materials typically fail at lower stress in shear than in tension. For steel fasteners, shear strength is approximately 60% of tensile strength.

How do I choose the right fastener grade?

Consider the load requirements, environmental conditions (corrosion), and application type. Higher grades offer more strength but may be more brittle.

Does thread type affect load capacity?

Yes, threaded sections have reduced cross-sectional area (stress area). This calculator uses nominal diameter; for precise calculations, use the tensile stress area.

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