Hoist Motor Power Calculator

Enter the mass of the object, the velocity of the raise motion, and the efficiency of the hoist into the calculator to determine the power.

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Hoist Motor Power Formula

Hoist motor power is the mechanical power required to raise a load vertically at a target speed while accounting for efficiency losses in the hoist, gearbox, chain, rope, drum, and related components. This calculator is most useful for estimating the minimum running power needed for a steady lift.

P = \frac{m \cdot g \cdot v}{\eta}

If efficiency is entered as a percentage for manual calculation, convert it to a decimal first.

\eta = \frac{\eta_{\%}}{100}

How the Formula Works

The load creates a lifting force equal to its weight. Power is force multiplied by vertical speed, then adjusted upward to account for losses. A less efficient hoist requires more motor power to achieve the same lift rate.

F = m \cdot g

P = \frac{F \cdot v}{\eta}

• If the load doubles, the required power doubles.
• If the lifting speed doubles, the required power doubles.
• If efficiency decreases, the required motor power increases.

How to Calculate Hoist Motor Power

1. Determine the total mass being lifted, not just the payload.
2. Measure or specify the vertical raising speed of the hook or load.
3. Determine the overall hoist efficiency and convert percent to decimal if calculating manually.
4. Multiply mass by gravity and lift speed.
5. Divide by efficiency to find the required motor power.
6. Convert watts to horsepower if needed for motor comparison.

hp = \frac{P}{745.7}

Example Calculation

Suppose a hoist raises a 10 kg load at 0.25 m/s with an efficiency of 65%.

P = \frac{10 \cdot 9.81 \cdot 0.25}{0.65}

P = 37.73 \ \mathrm{W}

That is approximately 0.0506 hp. This value represents the theoretical continuous power needed to maintain the lift under the stated conditions.

What This Result Means

The calculated result is best treated as a baseline operating power. Real hoist motor selection often requires additional capacity for startup torque, acceleration, braking, duty cycle, shock loading, temperature rise, and long-term reliability. In practice, the motor chosen is usually larger than the theoretical minimum.

Assumptions Behind This Calculator

• The lift is primarily vertical.
• The load is raised at a steady average speed.
• The entered efficiency reasonably represents total system losses.
• No extra allowance is included for sudden starts, impacts, or overload events.

Practical Input Tips

• Include hooks, slings, fixtures, and lifting hardware in the total mass.
• Use the actual hook speed or load speed, not the motor shaft speed.
• Use a realistic efficiency value; idealized values can understate power needs.
• When calculating manually, keep units consistent throughout the equation.
• If the hoist uses a reeving arrangement, use the actual load travel speed for the lift.

Common Mistakes

• Using payload mass instead of total lifted mass.
• For manual calculation, forgetting to convert 65% efficiency to 0.65.
• Using horizontal travel speed instead of vertical lifting speed.
• Assuming the formula alone is enough for final motor sizing in heavy-duty applications.

Frequently Asked Questions

Does a heavier load always require more power?

Yes. With speed and efficiency unchanged, required hoist motor power increases in direct proportion to the lifted mass.

Does lifting faster require more power?

Yes. Power rises linearly with lifting speed, so faster lifting requires proportionally more motor power.

Why does efficiency matter so much?

Efficiency accounts for the losses between the motor and the load. As efficiency drops, the motor must supply more input power to deliver the same useful lifting power.

Is this calculator for motor sizing or power estimation?

It is primarily a power estimation tool. It gives a strong first-pass estimate, but final hoist motor selection should also consider torque, thermal limits, duty classification, and safety margin.