Online Bolt Torque Calculator

This tool is designed to help engineers, mechanics, and DIY enthusiasts calculate the torque required for bolted connections to ensure proper fastening. By considering factors such as bolt material, size, and thread type, the calculator simplifies complex torque calculations, promoting safety, reliability, and assembly efficiency.

Bolt Data

Bolt Type (Inch): Major Diameter (in): Bolt Material: Bolt Proof Strength (psi):

Thread Data

Thread Engagement Length (in): Thread Material: Thread Yield Strength (psi):

Torque Coefficient (K-Factor)

The K-Factor is an empirical coefficient to account for friction. It depends on the bolt material, thread type, surface finish, coatings, and lubrication. Typically ranges from 0.1 to 0.3.

Results will appear here after the calculation.

Disclaimer:

This Bolt Torque Calculator is provided as a tool for informational purposes only. While we strive for accuracy, we do not guarantee the correctness or completeness of the results. Users are solely responsible for verifying the calculations and ensuring their suitability for any specific application. Manufacturer data should always take precedence. We accept no liability for any damages, losses, or injuries resulting from the use of this calculator.

FAQ

What is torque in the context of bolts?

Torque refers to the rotational force applied to a bolt or fastener to ensure proper tightening. It is measured in units such as Newton Meter (N⋅m) or Pound-force Inch (lbf⋅inch).

What happens if a bolt is over-torqued?

Over-torquing can cause thread stripping, bolt deformation, or breakage, compromising the assembly’s integrity.

What happens if a bolt is under-torqued?

Under-torquing may result in insufficient clamping force, leading to loosening, vibration, or component failure.

How lubrication affect torque calculations?

The K-Factor (Torque Coefficient) represents the relationship between the applied torque and the actual clamping force, taking friction into account. It depends on the materials involved, the size of the bolt, and the type of lubrication. Typically, the K-Factor—and, therefore, the required torque—can be reduced by around 10% for light lubrication, and by about 40% for bolts lubricated with oil.

Which industry standards are used for bolt torque calculations?

Several industry standards are used depending on the type of bolted joints and specific applications. Common standards include:
ASME B1.1: Defines Unified Inch Screw Threads, providing essential thread geometry specifications that form the foundation for torque calculations.
ISO 16047: Specifies testing methods for determining the relationship between torque and clamp force in threaded fasteners.
ISO 898-1: Specifies mechanical properties and strength classification for steel fasteners.
VDI 2230: Calculation and design of high-duty bolted joints in mechanical and structural engineering.
ASTM F606/F606M: Testing methods for mechanical properties of externally and internally threaded fasteners in industrial applications.
SAE J1199: Focuses on torque-tension relationships for automotive and light industrial fasteners.
MIL-STD-1312-15: For military and aerospace applications.
NASA/TM-2017-219475: Installation torque tables for noncritical applications based on experience in aerospace applications.

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