Configuration
INCH
METRIC
Recommended Torque & Clamp Load
Clamp Load
—
lbs
Clamp Load
—
N
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Select your configuration above to calculate torque, tension, and clamp load values.
Add up to 4 configurations from the Calculator tab to compare side-by-side.
Side-by-Side Comparison
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Use the Calculator tab to add configurations for comparison (up to 4).
Important Disclaimer
This calculator is a guide to estimate torque values. Use of its content by anyone is the sole responsibility of that person and they assume all risk. Due to many variables that affect the torque-tension relationship — including human error, surface texture, and lubrication — the only way to determine the correct torque is through experimentation under actual joint and assembly conditions.
This calculator is a guide to estimate torque values. Use of its content by anyone is the sole responsibility of that person and they assume all risk. Due to many variables that affect the torque-tension relationship — including human error, surface texture, and lubrication — the only way to determine the correct torque is through experimentation under actual joint and assembly conditions.
When tightening is critical to the application: SELECT TORQUE BY EXPERIMENTATION
Recommended procedure: torque 10+ parts to failure in the actual application. Average the failure torque. Seating torque should be 65%–75% of average failure torque.
Recommended procedure: torque 10+ parts to failure in the actual application. Average the failure torque. Seating torque should be 65%–75% of average failure torque.
Calculation Method
| Formula | T = KDP — where T = Torque, K = Torque Coefficient (dimensionless), D = Nominal Diameter, P = Bolt Clamp Load |
| Clamp Load Basis | 83% of minimum proof load for each grade and size (adjustable via slider) |
| K — Waxed (pressure wax) | 0.10 |
| K — Hot Dip Galvanized | 0.25 |
| K — Plain / As Received | 0.20 |
| Tension Variability | Bolt tension varies ±25% when tightened with an indicating torque wrench |
Standards & References
| ISO 898-1 | Mechanical properties of fasteners — Carbon and alloy steel bolts, screws and studs (Metric) |
| ISO 3506 | Mechanical properties of corrosion-resistant stainless steel fasteners (Metric) |
| ISO 965-1 | ISO general purpose metric screw threads — Tolerances (Metric thread geometry) |
| SAE J429 | Mechanical and material requirements for externally threaded fasteners (Inch) |
| ASTM F593 | Stainless steel bolts, hex cap screws, and studs (Inch) |
| ASTM A193 | Alloy-steel and stainless steel bolting for high-temperature or high-pressure service (Inch) |
| ASME B1.1 | Unified Inch Screw Threads (UN and UNR) — Inch thread geometry and tolerances |
| ASTM F1941 | Electrodeposited coatings on threaded fasteners |
| ASTM F1136 | Zinc/aluminum corrosion protective coatings on fasteners |