● System Active
BOLTCALC TORQUE & CLAMP FORCE CALCULATOR
Tightening Torque
—
N·m
🔩 TORQUE
Clamp Force
—
kN
⇧ CLAMP
Stress Area
—
mm²
Bolt Stress
—
MPa
K Factor
—
nut factor
Bolt Cross-Section
Bolt Size — Metric (M)
📊
Grade 8.8 · High Strength
Min tensile 800 MPa · Proof 640 MPa · Common structural fastener
Parameters
Bolt Grade8.8
Friction ConditionLightly Oiled
Preload (% of Proof)75%
50%70%90%
Safety Factor1.0×
1.0×2.0×3.0×
Formula Reference
TRQT = K × Fi × d  ·  K = nut factor (surface friction)
CLFFi = σp × As × η  ·  η = preload ratio
AREAAs = π/4 × (d − 0.9382p)²  ·  p = thread pitch
📚 Recommended Book
RS
KHURMI
—
MACHINE
DESIGN
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Theory of Machines & Machine Design
by R.S. Khurmi & J.K. Gupta
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The go-to reference for mechanical engineers. Covers fasteners, bolt design, shafts, springs, gears & more — everything this calculator is based on.
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