How to Convert Nm to ft-lb (and ft-lb to Nm)

What Is a Newton-Meter (Nm)?

A Newton-meter (N·m) is the SI unit of torque — the rotational equivalent of a force. One Newton-meter is the torque produced by a force of one Newton applied perpendicular to a lever arm one meter long.

Newton-meters are used in most of the world for engine specifications, bolt torque values, and engineering calculations. If you are reading a European or Japanese vehicle manual, torque will almost certainly be listed in Nm.

What Is a Foot-Pound (ft·lb)?

A foot-pound (ft·lb) is the imperial unit of torque used primarily in the United States. It represents the torque produced by a force of one pound applied at a distance of one foot.

American automotive manuals, torque wrenches sold in the US, and engine specifications from US manufacturers use foot-pounds. Smaller values — such as those for interior trim bolts or electronic connectors — are often listed in inch-pounds (in·lb), where 1 ft·lb = 12 in·lb.

The Conversion Formula

The exact conversion factor is: 1 ft·lb = 1.35582 Nm, or equivalently, 1 Nm = 0.73756 ft·lb.

To convert Nm to ft·lb: multiply by 0.7376. Example: 100 Nm × 0.7376 = 73.76 ft·lb.

To convert ft·lb to Nm: multiply by 1.3558. Example: 80 ft·lb × 1.3558 = 108.5 Nm.

Quick mental shortcut: divide Nm by 1.36 for ft·lb, or multiply ft·lb by 1.36 for Nm. This gives results within 0.03% of the exact value.

Nm to ft·lb Reference Table

Common torque values converted between both systems:

• 10 Nm = 7.4 ft·lb
• 20 Nm = 14.8 ft·lb
• 50 Nm = 36.9 ft·lb
• 80 Nm = 59.0 ft·lb
• 100 Nm = 73.8 ft·lb
• 120 Nm = 88.5 ft·lb
• 150 Nm = 110.6 ft·lb
• 200 Nm = 147.5 ft·lb

Real-World Torque Values

Lug nuts (wheel bolts): Most passenger cars require 80–120 Nm (59–89 ft·lb). Always check the sticker inside the driver's door jamb or the owner's manual — over-torquing can warp brake rotors or strip threads.

Spark plugs: Typically 15–30 Nm (11–22 ft·lb) depending on thread size. Aluminum cylinder heads require less torque than cast iron.

Cylinder head bolts: Usually 50–100 Nm (37–74 ft·lb) in multiple stages. Many modern engines use torque-to-yield (TTY) bolts that must be replaced after removal.

Engine output: A typical family car produces 150–250 Nm (110–184 ft·lb) of torque. Sports cars often exceed 400 Nm (295 ft·lb), while diesel trucks can exceed 1,000 Nm (737 ft·lb).

Inch-Pounds vs Foot-Pounds

For small fasteners — interior trim, electronics, small engine components — torque values are often given in inch-pounds (in·lb) rather than foot-pounds.

The conversion is simple: 1 ft·lb = 12 in·lb. So 18 in·lb = 1.5 ft·lb = 2.03 Nm.

When a spec sheet says "15 in·lb," do not confuse it with 15 ft·lb — that would be eight times too much and could strip the fastener.

Conclusion

The key number to remember: 1 ft·lb ≈ 1.356 Nm. For quick mental math, dividing Nm by 1.36 gives ft·lb within rounding error. Use our free torque converter for any exact value, and always double-check critical torque specs against your vehicle's service manual. Always consult a qualified mechanic for safety-critical fasteners.