Waliv, Vasai East, Maharashtra +91 8669118834
Gurukrupa Enterprises
Industrial Cost Calculators

Motor Running Cost Calculator

Calculate the electricity running cost of a motor from its HP, load factor and efficiency.

Calculate

Result
—
Copied

About this calculator

Motors rarely run at exactly 100% of their rated load all the time. This calculator estimates realistic running cost by factoring in the average load a motor actually operates at, alongside its rated HP and efficiency, giving a more accurate cost figure than assuming full-load operation throughout.

Formula

Input kW = (HP × 0.7457 × Load%) ÷ η; Cost = Input kW × Hours × Days × Rate
  • HPMotor rated output — horsepower
  • Load%Average operating load as % of rated — 0–1
  • ηMotor efficiency — 0–1
  • RateElectricity tariff — currency per kWh

Worked Example

Given: A 20 HP motor runs at 80% average load, 90% efficiency, 10 hrs/day, 26 days/month, at ₹8/kWh.

Result: Input kW = (20×0.7457×0.8)÷0.9 = 13.26 kW. Monthly cost = 13.26×10×26×8 = ₹27,590.

How to Use

  1. Enter the motor's rated output in HP.
  2. Enter its typical average load factor as a percentage of rated output (commonly 70–90% for most industrial applications).
  3. Enter its efficiency from the nameplate.
  4. Enter running hours per day, working days per month, and your electricity rate.
  5. Click Calculate for the estimated running cost.

Important Assumptions

  • Assumes efficiency stays roughly constant with load, which is a reasonable approximation between about 50–100% load for most induction motors, but becomes less accurate at very light loads.
  • Load factor should be based on actual measurement (clamp meter/energy meter) where possible for best accuracy.

Common Mistakes

  • Always assuming 100% load factor, which usually overstates real running cost — most industrial motors average well below their nameplate rating in normal duty.

Frequently Asked Questions

How do I find my motor's actual average load factor?

Measure current with a clamp meter and compare to the nameplate full-load current, or use an energy logger over a typical production cycle for the most accurate figure.

Does starting current affect this running cost estimate?

No — starting (inrush) current lasts only a few seconds and has negligible effect on overall energy cost compared to running load.

These calculators are provided for informational and estimation purposes. Results depend on the assumptions and input values used. Always verify critical engineering calculations against applicable standards, manufacturer specifications, site measurements, and qualified professional advice.