About the Bolt Torque Calculator Online Free Tool

The Bolt Torque Calculator Online Free Tool estimates tightening torque from target preload, nominal bolt diameter, and nut factor using the common T = KFD approximation.

How to Use the Bolt Torque Calculator Online

1. Enter the desired bolt preload in newtons.
2. Enter nominal bolt diameter in millimeters and the nut factor for the joint condition.
3. Run the calculator to review tightening torque in N.m and lbf.in.

Choosing Options Correctly

Nut factor strongly depends on thread condition, lubrication, coating, washer surface, and assembly method. Critical joints should use tested torque-tension data or direct tension control rather than this simple estimate alone.

Common Use Cases

• Estimate workshop torque for non-critical bolted joints.
• Compare dry and lubricated nut-factor assumptions.
• Convert a preload target into a quick torque value.

Quick FAQ

Is this a substitute for torque-tension testing?
No. The nut factor is only an estimate, and friction variation in threads, washers, coatings, and lubrication can dominate the final clamp load.

Does it account for bolt grade?
No. Use the result only after checking the target preload against the bolt proof load and the joint requirement.

What nut factor should I use?
Use a value from test data, a fastener supplier, or your assembly standard. Dry, plated, and lubricated hardware can need very different torque.

Can I use this for critical joints?
Treat it as a starting estimate only. Critical joints should use controlled tightening procedures, torque-angle data, direct tension measurement, or a qualified joint design.