Electric Motor Energy Savings & Payback Calculator

See how much you save by switching to a higher-efficiency electric motor (IE3 → IE4 → IE5). Annual energy & cost savings and simple payback.

Motor power (kW)

Operating hours / year

Electricity price (per kWh)

Load factor (0-1)

Old efficiency η₁ (%)

New efficiency η₂ (%)

Price difference of new motor (optional, for payback)

Annual energy saving: — kWh

Annual cost saving: —

Simple payback: — months

kWh = P · load · hours · (1/η₁ − 1/η₂)

Why efficiency class matters

A higher electric motor efficiency class (IE3/IE4/IE5) draws less electrical input for the same shaft power, so savings accrue every operating hour. For motors running many hours/year the energy cost far exceeds the purchase price over the lifetime — upgrading to IE4/IE5 typically pays back in months. DRG Motor supplies IE3/IE4/IE5 motors from 0.55 to 355 kW.

Efficiency classes (illustrative, 4-pole)

Class	Name	≈ Efficiency (11 kW)
IE2	High	~89.8%
IE3	Premium	~91.4%
IE4	Super Premium	~92.6%
IE5	Ultra Premium	~93.3%

Values are indicative and vary with rated power and pole count; always use the nameplate/datasheet efficiency.

Frequently asked questions

Is it worth upgrading to a higher-efficiency motor?

For motors running many hours per year, yes. The energy cost over a motor's life is far greater than its purchase price, so even a few efficiency points (IE3→IE4→IE5) usually pay back the price difference within months.

What is the difference between IE3, IE4 and IE5?

They are IEC efficiency classes: IE3 (Premium), IE4 (Super Premium) and IE5 (Ultra Premium). Each higher class has lower losses and higher efficiency for the same rated power.

How is annual saving calculated?

Saving (kWh) = P · load factor · operating hours · (1/η₁ − 1/η₂). Multiply by the electricity price for the cost saving.

How is payback calculated?

Simple payback (months) = price difference of the new motor ÷ monthly cost saving. Enter the price difference in the calculator to see it.

What is the load factor?

The average fraction of rated power the motor actually delivers (0–1). A motor sized with margin often runs at 0.7–0.9 load.