Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Shaft Power Watts (W)

Required number input.

Speed Rpm (rpm)

Required number input.

Shaft torque from mechanical shaft power and rotational speed: T=P/(2πn/60). The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Torque Newton Meters (N·m)

The resulting torque newton meters returned as a number.

• Motor speed, slip, torque, and power depend on motor type, voltage, frequency, drive, winding temperature, efficiency, power factor, saturation, cooling, and load curve. Nameplate or ideal relations do not define transient or thermal capability.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Power Torque RPM

  Mechanical shaft power from torque and revolutions per minute using P=T·2πn/60.

• Critical Shaft Speed

  Undamped first critical rotational speed estimated from a measured static shaft deflection under gravity: n=30√(g/δ)/π.

• Propeller Efficiency

  Propulsive efficiency as thrust times advance speed divided by shaft power; assumes steady straight-ahead motion.