Energy Cost Calculator - kWh Price and Running Cost

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

Running cost is just energy use multiplied by your electricity rate. The trick is using real hours and real watts. A heater is easy. A fridge, AC or pump cycles, so use average duty cycle if you want a bill that looks like reality.

Formula at a glance

  • kWh = watts x hours / 1000
  • cost = kWh x price per kWh
  • monthly cost = daily cost x days

Field note: If the bill feels high, find the loads that run longest first. A small device running all day can beat a big device used for ten minutes.

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Energy Cost Calculator

kWh
USD/kWh
Result
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Formula

Cost = kWh × Rate

How to use the Energy Cost Calculator

Use this as a unit check for energy, power and time. Keep the time period honest, because a one-hour run and a one-month run can make the same load look completely different.

Worked example

Example: 2,000 W for 3 hours is 6 kWh. At $0.16 per kWh, that is $0.96 for the run.

Practical checks before you trust the number

  • For AC units, use actual input watts, not cooling BTU.
  • For motors, power factor matters when converting from amps to watts.
  • Commercial bills may include demand charges, not just kWh.

Common mistake

If the bill feels high, find the loads that run longest first. A small device running all day can beat a big device used for ten minutes.

Sources and references

Related calculators

Frequently Asked Questions

Cost = kWh × tariff (I/kWh). Example: 100 kWh × I6 = I600. Add fixed charges and taxes for the total bill. This is the most basic energy economics formula and the foundation of every payback analysis we do.

Total cost = (W × hours ÷ 1000) × tariff per kWh + fixed charges. Example: a 2000 W heater running 4 hours/day for a month at I6/kWh = (2000 × 4 × 30 ÷ 1000) × 6 = I1440/month. Plus fixed and taxes for the actual bill impact.

(1000 × 1 ÷ 1000) × I6 = I6 per hour. So running 1 kW for one hour costs I6 at a I6/kWh tariff. Adjust for your local rate — in some states it's I4, in others I8 to I10 for higher slabs.

Monthly cost = (W × hours/day × 30 ÷ 1000) × tariff. Example: 1500 W AC × 6 hours × 30 days × I7/kWh = I1890/month. Multiply across appliances and add fixed charges for total expected bill.

Use your actual tariff from your latest electricity bill. For Indian residential, typical rates are I4 to I8/kWh depending on slab and state. For commercial, I8 to I12/kWh. For industrial with TOD, I6 to I14/kWh depending on time slot. Don't use generic averages — they can be off by 30% or more.

Multiply your peak-hour kWh by the peak rate, off-peak kWh by the off-peak rate, and sum. Example: 50 kWh peak at I10 + 100 kWh off-peak at I5 = I500 + I500 = I1000. Many industrial customers shift heavy loads to off-peak hours to save 30 to 50% on energy costs.

Yes. Enter old and new appliance watts and runtimes. The calculator shows monthly and annual savings. Example: replacing a 200 W tube light bank with 80 W LEDs running 8 h/day saves 120 W × 8 × 30 = 28.8 kWh/month, or about I200/month at I7/kWh. Payback usually under a year.