Bolt Torque Calculator

Estimate bolt tightening torque and clamp load for M8 to M30 fasteners across property classes 4.6 to 12.9, adjusted for the friction coefficient.

Estimate tightening torque and clamp load for common metric bolts. Always verify against manufacturer specifications and site procedures.

Bolt Size

Bolt Grade

Friction Coefficient (K)Typical values: 0.12–0.15 for lubricated, 0.17–0.20 for dry unlubricated fasteners

Applied TorqueTorque applied to the fastener

N·m

Clamp Load

79.17 kN

≈ 8.07 tonnes-force

Estimated Clamp Load

79.17 kN

≈ 17.80 kip

Recommended Torque

163.91 N·m

Grade 8.8 · Preload 68.30 kN · ≈ 120.89 lbf·ft

Short-form approximation only. For critical joints use the manufacturer's torque chart or a calibrated method (angle / yield / stretch).

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These calculators are provided as a guide only. Always verify critical calculations with a qualified engineer before implementation.