Motor Energy Cost Calculator

About the Motor Energy Cost Calculator

This motor energy cost calculator calculates annual and 20-year electricity cost for any electric motor based on HP, efficiency, load factor, runtime hours, and your local energy rate. Use it to budget motor operating costs, build the business case for Premium-efficiency upgrades, justify VFD installations, or compare motor purchase options on a true total-cost-of-ownership (TCO) basis.

Over a typical 15–20 year service life, electricity cost dwarfs the motor purchase price by 25–50× for continuous-duty applications. This calculator quantifies that often-hidden cost.

How motor energy cost is calculated

Input kW = (HP × 0.7457 × Load Factor) ÷ Efficiency
Annual Cost = Input kW × Hours/Year × $/kWh

The conversion factor 0.7457 converts HP to kW (1 HP = 0.7457 kW). Load factor accounts for actual operating load (1.0 = full nameplate, 0.5 = half). Efficiency reduces the useful output below input power. Annual hours range from 2,000 (1-shift) to 8,760 (24/7).

Worked example

A 25 HP motor at 92% efficiency, running at full load 4,000 hours/year at $0.12/kWh: Input kW = (25 × 0.7457 × 1.0) ÷ 0.92 = 20.26 kW. Annual cost = 20.26 × 4000 × 0.12 = $9,725/year. 20-year cost = $194,500 — far more than the motor itself ever cost.

When to use this calculator

• Budgeting motor electricity costs for plant operations
• Building the business case for upgrading to NEMA Premium motors
• Comparing TCO of standard vs Premium motor purchases
• Justifying VFD installations for variable-load applications
• Evaluating utility rebate programs (often based on annual savings)
• Calculating ROI for motor replacement vs rewind decisions
• Supporting energy audit and ISO 50001 documentation

Typical electricity rates (Canada)

• Quebec: $0.075/kWh (lowest in North America — hydroelectric)
• Manitoba/BC: $0.10/kWh (hydro-dominant grids)
• Ontario: $0.10–$0.18/kWh (time-of-use tiered)
• Alberta: $0.12–$0.18/kWh (deregulated, variable)
• Atlantic Canada: $0.13–$0.17/kWh
• Industrial demand charges: add $5–$15/kW peak demand on top of energy ($/kWh)

Frequently Asked Questions

Why does motor efficiency matter so much?

Over 20 years, electricity cost is typically 25–50× the motor purchase price for continuous-duty motors. A 3% efficiency improvement on a 50 HP motor running 8,000 hrs/year at $0.10/kWh saves about $1,000 per year — $20,000 over 20 years.

How do I find my motor’s efficiency?

From the nameplate. Modern Premium-efficiency motors are 90–96% depending on HP. Standard efficiency: 87–93%. Older (pre-1997): 80–88%. If unknown, use 90% as a conservative default.

What load factor should I use?

For continuous-duty motors at design conditions: 1.0 (full load). For oversized motors or variable applications: measure actual amperage and divide by FLA. Most industrial motors run at 60–85% load.

How accurate are these cost projections?

Within ±10–15% for the annual cost. The biggest sources of error: actual electricity rate (varies hourly under time-of-use), actual load (rarely 100% as nameplate), and demand charges (not included in this simple calculation).

Why is the 20-year cost so high?

Industrial motors run for 4,000–8,000+ hours per year. Over 20 years, that’s 80,000–160,000 hours of operation. Even at $0.10/kWh, a 25 HP motor consumes nearly $200,000 in electricity over its life. This is why motor efficiency dominates total cost of ownership.

Does this account for utility demand charges?

No — this calculates only energy ($/kWh). Industrial customers typically also pay demand charges ($/kW peak) which can add 30–50% to total motor cost. For a complete TCO, multiply this calculator’s result by 1.3–1.5.

Related calculators and Electracore products

Considering a Premium-efficiency upgrade? Browse General Purpose motors or check IEC frame motors from Baldor, WEG, and Marathon.

Related calculators: Motor Efficiency Calculator · HP to Amps Calculator · VFD Sizing Calculator · kW to HP Calculator.