Bolt Torque Calculator
Enter bolt diameter, clamp force, and torque coefficient to instantly calculate required tightening torque.
Use the Bolt Torque Calculator
Bolt Parameters
Quick presets:
Result
Fill in the parameters and click Calculate.
Tightening Torque
—
Newton-meters (N·m)
Equivalent In
—
foot-pounds (ft·lb)
Calculation Breakdown
Engineering approximation only. For structural or safety-critical joints, consult applicable standards (AISC, VDI 2230, ISO 16047) and a licensed engineer.
Summary
The Bolt Torque Calculator uses the standard engineering formula T = K × D × F to determine how much torque is needed to achieve the target clamp load on a bolted joint. Enter the nominal bolt diameter, the desired clamp force, and the nut factor (K) for your lubrication condition, and the tool instantly returns the tightening torque in both Newton-meters and foot-pounds. Presets for common K factors (dry, lubricated, zinc-plated, and waxed) speed up everyday fastener work.
How it works
- Enter the nominal bolt diameter in millimeters or inches.
- Enter the required clamp force in kilonewtons or kips.
- Select a nut factor (K) preset or type a custom value.
- Click "Calculate" to apply T = K × D × F.
- Read the tightening torque result in N·m and ft·lb.
- Use "Reset" to clear all fields and start a new calculation.
Use cases
- Determining torque specs for structural steel connections.
- Setting torque wrench values for engine and machinery assembly.
- Verifying fastener loads in bridge and civil construction.
- Calculating flange bolt torques for pipe and pressure-vessel work.
- Quick cross-check of manufacturer torque tables against field conditions.
- Teaching engineering students the nut-factor method.