How much does an efficient motor save?

It depends on the efficiency difference, the motor power, the load and the running time. The tool calculates the saving in kWh and cost; at high power and long running a small point difference becomes meaningful.

How do I find the efficiency of my current motor?

The nameplate or the manufacturer's data sheet shows the efficiency. For old or rewound motors the real efficiency can be lower than the nameplate; verify by power measurement if possible. Use the value at your operating load.

Which IE class should I choose?

The tool assumes no fixed efficiency for a class. Enter in the target field the efficiency the manufacturer gives for the class you choose, for your motor power and number of poles.

Why does load matter?

Power drawn depends on load, and efficiency falls in most motors below roughly half load. If the load is low, the savings potential may come from correct sizing or a variable speed drive rather than from a more efficient motor.

Why do I enter the CO₂ factor myself?

The factor varies with the grid mix, the year and the calculation method. Rather than use a wrong ready-made value, you are asked to enter the factor from your valid source; if left empty, CO₂ is not calculated.

Motor efficiency savings calculator

Enter the motor's power, load and running time, and the current and target efficiency. See the annual energy and cost savings of moving to a more efficient motor, and the payback time.

Free tool · Predictive maintenance

Motor rated power (shaft)kWThe output power on the motor nameplate.Load%Average operating load of the motor as a share of rated power.

Operating time per yearh/yearTotal hours the motor runs in a year.

Current efficiency%Efficiency at the operating load; nameplate, manufacturer data sheet or measurement. Only a typical range is given below.Target efficiency%Efficiency of the new motor at the same load; enter it from the manufacturer's data sheet.

Currency

Electricity unit priceEUR/kWhEnter your own tariff (the example value is for illustration only).Investment costEURNew motor and replacement labour (optional; for the payback).Evaluation periodyearsNumber of years for the net gain (optional; no discounting or price rise).Emission factor (optional)kg CO₂/kWhEnter the current factor published by your grid or electricity supplier; the tool suggests no ready value. If left empty, CO₂ is not calculated.

The calculation runs in your browser; the values you enter are not sent anywhere.

Typical range for efficiency

Motor efficiency varies with power, number of poles and efficiency class (IE). It is generally lower in small motors and higher in large ones and lies roughly between the eighties and the mid-nineties in percent. This is only for an idea of scale; for the calculation enter the value from your nameplate, the manufacturer's data sheet or your measurement.

Efficiency also depends on load: when load drops below about half of rated, efficiency falls in most motors. You therefore need to enter the value at your operating load; oversized motors create extra loss for that reason. No fixed value for IE classes is given here.

Annual cost savings: €1,068
Annual energy savings: 7,117 kWh/year
Reduction in energy: 2.65%
Simple payback time: 2.8 years
Net gain at the end of the evaluation period: €7,675
Current annual energy: 269,022 kWh/year · €40,353
New annual energy: 261,905 kWh/year · €39,286
Current power drawn from the grid: 44.84 kW
New power drawn from the grid: 43.65 kW

Sensitivity: efficiency gain

Sensitivity: efficiency gain
Target efficiency	Savings (kWh/year)	Savings (cost/year)
93 %	2,893	€434
94 %	5,724	€859
95 %	8,495	€1,274
97 %	13,867	€2,080

Each row shows a target with the stated percentage points added to the current efficiency. Even small point differences produce meaningful savings at high power and long running time.

Assumptions

Load and running time are constant; with variable load a load profile is more accurate than an average load.
Efficiency values belong to the operating load point and you enter them; the tool does not produce efficiency values of its own.
Discounting, electricity price rises, maintenance differences and the motor's residual value are not included; payback is simple payback.
Only the motor's own loss is evaluated; the efficiency of the drive, gearbox and driven machine is taken as constant.
CO₂ is calculated only with the factor you enter; the source and year of the factor are your responsibility.

P_out = rated power × load · P_in = P_out / η · savings = P_out · hours · (1/η_current − 1/η_target) · payback = investment / annual savings

The result is a first calculation based on the efficiency values you enter and the constant-load assumption; real savings depend on load, operating pattern and the motor's actual efficiency. Verify with measurements and manufacturer data before an investment decision.

Let's look at which motors in your motor and drive data run inefficiently, and at the priority for maintenance or replacement.

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How to use it

A
Enter the motor power, load and yearly operating time.
B
Enter the current and target efficiency (at the operating load), the electricity price and, if you have it, the investment cost.
C
Read the annual kWh and cost savings and the payback time; if you wish, see the CO₂ reduction with your own emission factor.

How the energy savings are calculated

The power a motor draws from the grid is the shaft output power divided by the efficiency. Output power is rated power times load. For the same work, a more efficient motor draws less electricity; multiplying the difference by the yearly operating hours gives the saving in kWh, and multiplying by the unit price gives the cost saving.

In industry a motor's lifetime energy cost is often many times its purchase cost. For long-running motors in particular, an efficiency difference that looks small can pay back the investment quickly.

Where to take the efficiency value from

The accuracy of the calculation depends on the efficiency values you enter. For the existing motor use the nameplate, the manufacturer's data sheet or a measurement; for the new motor the manufacturer's efficiency at the relevant load. The efficiency class (IE) is only a category, and within a class values vary with power; the tool therefore uses no fixed number for a class.

Efficiency varies with load: below roughly half load it falls noticeably in most motors. If a motor runs continuously at low load, a correctly sized (smaller) motor or a variable speed drive may save more than a more efficient motor of the same size.

Payback and its limits

Simple payback is the investment divided by the annual savings. It ignores price rises, discounting, maintenance differences and the motor's scrap value; it is suitable for a first screening, not for the final investment decision. When deciding between repairing a failed motor and replacing it with an efficient one, the difference between the repair cost and the new motor can be entered as the investment.

The CO₂ reduction is the saved kWh times the factor you enter. The factor varies with the grid mix, the year and the calculation method; in official reporting use the factor published by the relevant authority or supplier.

FAQ

How much does an efficient motor save?: It depends on the efficiency difference, the motor power, the load and the running time. The tool calculates the saving in kWh and cost; at high power and long running a small point difference becomes meaningful.
How do I find the efficiency of my current motor?: The nameplate or the manufacturer's data sheet shows the efficiency. For old or rewound motors the real efficiency can be lower than the nameplate; verify by power measurement if possible. Use the value at your operating load.
Which IE class should I choose?: The tool assumes no fixed efficiency for a class. Enter in the target field the efficiency the manufacturer gives for the class you choose, for your motor power and number of poles.
Why does load matter?: Power drawn depends on load, and efficiency falls in most motors below roughly half load. If the load is low, the savings potential may come from correct sizing or a variable speed drive rather than from a more efficient motor.
Why do I enter the CO₂ factor myself?: The factor varies with the grid mix, the year and the calculation method. Rather than use a wrong ready-made value, you are asked to enter the factor from your valid source; if left empty, CO₂ is not calculated.

Prioritise your motors with data

Let's look at which motors in your motor and drive data run inefficiently or close to failure, and at the replacement priority.

Request a conversation Explore the predictive maintenance service →