Bolt Torque Calculator

• Free online bolt torque calculator — works right in your browser, no installation needed
• Supports metric (M4-M30) and imperial (1/4"-1") bolts, calculating the recommended tightening torque or preload based on strength grade, lubrication state and torque coefficient
• Supports bidirectional calculation of "Preload → Torque" and "Torque → Preload", showing proof load, tensile stress area, preload utilization, bolt stress and more, with one-click copy of the result

1. Open the tool page — no download or installation required
2. Choose "Preload → Torque" or "Torque → Preload" in "Calculation Mode", then pick the "Bolt Standard" (Metric/Imperial), bolt size, strength grade and lubrication state
3. Enter the preload or torque value according to the selected mode and choose the matching unit (kN/N/lbf or Nm/ft-lb/in-lb); if you select the "Custom" lubrication, also set the torque coefficient K
4. Click "Calculate" to view the recommended torque or preload and related results, then click "Copy" to copy the result with one click

• This tool is completely free and requires no registration or login
• All calculations happen locally in your browser — your data is never uploaded
• Results are for reference only. Follow the equipment manufacturer's specifications for actual assembly; use a calibrated torque wrench for critical joints

Free online bolt torque calculator supporting metric (M4-M30) and imperial (1/4"-1") bolts. Calculate recommended tightening torque or preload based on strength grade, lubrication state and torque coefficient. Useful for mechanical assembly, automotive repair and engineering.

Open the tool page — no download or installation required Choose "Preload → Torque" or "Torque → Preload" in "Calculation Mode", then pick the "Bolt Standard" (Metric/Imperial), bolt size, strength grade and lubrication state Enter the preload or torque value according to the selected mode and choose the matching unit (kN/N/lbf or Nm/ft-lb/in-lb); if you select the "Custom" lubrication, also set the torque coefficient K Click "Calculate" to view the recommended torque or preload and related results, then click "Copy" to copy the result with one click

This tool is completely free and requires no registration or login All calculations happen locally in your browser — your data is never uploaded Results are for reference only. Follow the equipment manufacturer's specifications for actual assembly; use a calibrated torque wrench for critical joints

Yes, Bolt Torque Calculator is completely free. No download or installation required — it runs right in your browser.