Force & Torque Converter

Frequently Asked Questions

What is the difference between force and torque?

Force is a straight-line push or pull (newtons, lbf, kgf). Torque is a twisting/rotational effort - force times lever-arm distance (N·m, lb·ft). They are different physical quantities, so the tool keeps them in separate modes.

How many newtons is a pound-force?

1 lbf = 4.4482 N; 1 kgf = 9.80665 N. For torque, 1 lb·ft = 1.3558 N·m and 1 kgf·m = 9.80665 N·m. Conversions pivot through the SI base (newton / newton-metre).

Is lb-ft the same as ft-lb?

For torque they are used interchangeably (pound-foot). Be careful not to confuse torque lb·ft with the energy unit foot-pound - same words, different quantity.

Why does kgf appear?

Kilogram-force (kgf or kp) is a legacy gravitational unit still common on some specs; it is the weight of 1 kg under standard gravity = 9.80665 N.

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This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

Force and torque are related but physically distinct quantities, so this tool keeps them in separate modes. Force is a push or pull; its SI unit is the newton (N), defined as the force that accelerates one kilogram at one metre per second squared (1 N = 1 kg·m÷s²). Torque is a twisting effect - force applied at a distance from a pivot - and its SI unit is the newton-metre (N·m). In each mode every unit is stored as a fixed number of base units, and conversion pivots through that base: result = amount × (baseFrom ÷ baseTo). For force the key factors are 1 lbf = 4.4482216 N, 1 kgf = 9.80665 N, 1 dyne = 10−5 N, 1 poundal = 0.13825495 N, and 1 ozf = 0.27801385 N. For torque, 1 lb·ft = 1.35581795 N·m, 1 lb·in = 0.11298483 N·m, 1 kgf·m = 9.80665 N·m, and 1 oz·in = 0.00706155 N·m. Although a newton-metre is dimensionally a joule, torque is never expressed in joules because the force and the lever arm are perpendicular vectors, not energy.

Worked Example

A bolt spec calls for 25 lb·ft of torque and your beam wrench reads in N·m. Step 1: 25 × 1.35581795 = 33.895 N·m. Step 2 (already in the target unit): set the wrench to about 33.9 N·m. Reverse a metric spec: a 90 N·m caliper bolt is 90 ÷ 1.35581795 ≈ 66.4 lb·ft. For force, a 50 kgf spring scale reading equals 50 × 9.80665 = 490.3 N, or 490.3 ÷ 4.4482216 ≈ 110.2 lbf. Notice kgf and kgf·m both use g = 9.80665 m÷s² - the same standard-gravity constant that defines a kilogram-force.

Where You Use This

Mechanics and technicians convert fastener torque specs between lb·ft, lb·in, and N·m on every service job - manufacturers publish in whichever system their market uses. Structural and mechanical engineers move between newtons, kilonewtons, and kilogram-force when reading loads from European versus US datasheets. Physics students convert dynes and poundals in classical-mechanics problems. Aerospace and robotics teams specify actuator output in N·m or oz·in for small servos.

Common Mistakes

Mixing force and torque: a newton is not a newton-metre. Always pick the correct mode - that is why they are separated here.

lb·ft vs ft·lb: these are the same torque unit written two ways; do not treat the reversed wording as different.

Torque vs energy: N·m for torque is not the same physical quantity as the joule (N·m of energy), despite identical units.

kgf rounding: using 9.81 instead of 9.80665 for kgf or kgf·m introduces a small but compounding error on big loads.

Ounce-inch scale: oz·in is tiny (≈0.00706 N·m); confusing it with lb·in (16× larger) badly under- or over-torques small fasteners.

Reference Factor Table

1 lbf = 4.4482216 N = 0.4535924 kgf = 138254.95 dyne

1 kgf = 9.80665 N = 2.2046226 lbf = 70.93164 poundal

1 N = 100000 dyne = 0.2248089 lbf = 7.2330114 poundal

1 lb·ft = 1.3558179 N·m = 12 lb·in = 0.1382550 kgf·m

1 N·m = 0.7375621 lb·ft = 8.8507458 lb·in = 0.1019716 kgf·m

1 kgf·m = 9.80665 N·m = 7.2330139 lb·ft

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