What bolt torque should I use?

Bolt torque depends on bolt size, property class/grade, and surface condition. Most common: M10 Class 8.8 = 50.5 N·m (37.2 ft·lbs) dry; 3/8" Grade 5 = 30.9 ft·lbs (41.9 N·m). Use this database to look up exact specifications for your bolt.

What is the difference between N·m and ft·lbs?

Both measure torque (rotational force). 1 ft·lb = 1.35582 N·m. Metric (ISO) specs use N·m; SAE/imperial specs use ft·lbs. To convert: multiply ft·lbs by 1.356 to get N·m, or multiply N·m by 0.738 to get ft·lbs.

What is an ISO 8.8 bolt?

ISO 8.8 (often called 'Grade 8.8') is a metric property class defined in ISO 898-1. The first digit (8) represents 1/100 of the minimum tensile strength in MPa (800 MPa). The second digit (8) × the first = 64, representing 640 MPa minimum yield strength. Class 8.8 is the most common high-strength metric fastener.

Bolt Torque Specs: M3–M64 & SAE #6–1-1/2"

261 bolt specifications

ISO 898-1 & SAE J429

6 surface conditions

Coarse & fine thread

102 vehicle lug nut specs

Popular Lookups

Metric Bolts (ISO)

M3 through M64, property classes 4.6 to 12.9. Complete torque specifications per ISO 898-1.

Browse 210 specifications →

Imperial Bolts (SAE)

#6 through 1-1/2", SAE grades 2, 5, and 8. UNC and UNF thread torque values per SAE J429.

Browse 51 specifications →

Lug Nut Torque by Vehicle

Torque, bolt pattern, thread size, socket and tightening sequence for 102 models across 19 makes — Toyota, Honda, Ford, Chevrolet, Tesla, Ram and more.

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