TUCA

Unit Converters

Torque Unit Converter and Power Calculator

Convert N·m to lb-ft, lb-in, and kgf-m, calculate rotational power, apply an efficiency reference, and compare torque with force times lever arm.

Torque (N·m)Rotational speed (rpm)Output torque efficiency (%)Entered torque comparison (N·m)Entered lever arm (m)Entered force comparison (N)

Torque in pound-feet-

Torque in pound-inches-

Torque in kilogram-force metres-

Power at entered rotational speed-

Torque after entered efficiency-

Torque minus entered comparison-

Force times lever arm-

Converted torque minus force-arm torque-

Decision view

Torque lever-arm and rotational-power diagram

Torque lever-arm and rotational-power diagramThe same N·m value is connected to perpendicular force, lever arm, shaft speed, power, efficiency, and converted units.

Exact scenario comparisonTorque (N·m) changes while all other entered assumptions remain constant.

Torque (N·m)	Torque in pound-feet	Torque in pound-inches	Torque in kilogram-force metres	Power at entered rotational speed	Torque after entered efficiency	Torque minus entered comparison	Force times lever arm	Converted torque minus force-arm torque

How to use Torque Unit Converter and Power Calculator

Enter torque in N·m.
Enter rotational speed and output efficiency when a power reference is needed.
Enter force and perpendicular lever arm for the independent mechanics comparison.
Read conversions separately from calculated power and force-arm torque.

Calculator guide

Understanding Torque Unit Converter and Power Calculator

Torque conversion preserves the same twisting moment in different unit systems. Power, efficiency-adjusted torque, and force at a lever arm are related calculations, not alternate torque units, so this page keeps them visibly separate.

Same physical moment Unit conversions preserve torque.

Power needs speed Torque alone does not determine kW.

Efficiency is separate It is not a unit conversion.

Force-arm check F times r independently recreates torque.

Calculation method

How the calculation works

Apply fixed mechanical unit factors to one torque value and independently connect torque with rotational speed, lever-arm force, efficiency, and an entered comparison. Multiply N·m by fixed unit factors, use angular speed to calculate power, apply the entered efficiency as a decimal, and independently calculate force-arm torque.

Detailed calculation process

Convert torque and connect it to speed and lever-arm force

The default converts 250 N·m, evaluates it at 3,000 rpm, applies 92% efficiency, and checks a 500 N force acting through a 0.5 m arm.

General formula: T_lb-ft = 0.7375621493T; T_lb-in = 8.850745791T; T_kgf-m = 0.1019716213T; P = 2pi nT/60000; T_e = eta T; T_F = Fr The first three equations change units without changing the physical torque. Power additionally depends on rotational speed. Efficiency reduces the reference output torque, while force times perpendicular lever arm provides an independent mechanics check.

What each symbol means

T Entered torque (N·m).

n Rotational speed (revolutions per minute).

P Mechanical power at the entered speed (kW).

eta, T_e Efficiency fraction and efficiency-adjusted torque (N·m).

F, r Perpendicular force (N) and lever arm (m).

T_F Torque implied by force and lever arm (N·m).

Worked substitution with the default inputs

1. Convert to imperial torque: 250 N·m * 0.7375621493 = 184.390537 lb-ft; 250 * 8.850745791 = 2,212.686448 lb-in Each fixed factor carries the destination unit per N·m.

2. Convert to kilogram-force metres: 250 N·m * 0.1019716213 = 25.492905 kgf-m Kilogram-force is a force unit under standard gravity, not a mass torque.

3. Calculate rotational power: P = 2pi(3,000 rpm)(250 N·m)/60,000 = 78.539816 kW The factor 60,000 combines seconds per minute and watts per kilowatt.

4. Apply efficiency: eta=92/100=0.92; T_e=0.92(250)=230 N·m The entered efficiency is a simplified output-torque reference.

5. Check force and lever arm: T_F=500 N * 0.5 m=250 N·m; gap=250-250=0 N·m The default perpendicular force-arm pair exactly reproduces the entered torque.

The default 250 N·m equals 184.391 lb-ft, produces 78.540 kW at 3,000 rpm, becomes 230 N·m at 92% efficiency, and matches the 500 N by 0.5 m force-arm check.

Mechanical geometry

See the force, arm, torque, and shaft speed together

The engineering diagram distinguishes a moment-arm construction from unit labels and power.

Pivot Torque acts around the rotation axis.

Lever arm Perpendicular distance controls moment.

Force vector Applied force creates the implied torque.

Rotational reference RPM connects torque to power.

Worked situations

Practical examples

250 N·m converts to 184.391 lb-ft.
At 3,000 rpm it corresponds to 78.540 kW.
A 500 N perpendicular force at 0.5 m also creates 250 N·m.

Better inputs

Useful tips

Confirm whether a specification uses lb-ft or lb-in.
Use perpendicular moment arm rather than raw lever length when force is angled.
Keep input and output shaft torque distinct when applying drivetrain efficiency.

Before relying on the result

Limitations and common mistakes

The efficiency adjustment is a simple scalar and does not model speed-dependent losses.
Dynamic torque, shock, harmonics, preload, friction, shaft rating, and tool calibration are excluded.
A converted value does not establish a safe design torque.

Reference

Key terms

Torque: Turning moment equal to force times perpendicular distance.
RPM: Revolutions per minute.
Moment arm: Perpendicular distance from the rotation axis to the force line.

Important note

Calculated directly from the entered values using the displayed formula and rounding settings.

Frequently asked questions

Are N·m and joules interchangeable?

They are dimensionally equivalent, but N·m is retained for torque to distinguish rotation from energy.

Why does power change with RPM?

Power equals torque times angular speed.

Does 92% efficiency always mean 230 N·m output?

Only in this simplified scalar reference; actual drivetrain loss depends on operating conditions.

What if the force is angled?

Use the perpendicular moment arm or the perpendicular component of force.