Skip to content
ENExplore Calculators

Energy Consumption (kWh) Calculator

Work out energy consumption (kwh) instantly with clear inputs, formula shown and shareable results.

About Energy Consumption (kWh) Calculator

Energy in kilowatt-hours is power in kilowatts multiplied by hours of use, and cost is energy times the tariff rate. The only common mistake is mixing watts with kilowatts: divide the appliance rating by 1,000 before multiplying by hours.

Formula

Energy and cost

kWh = watts / 1000 x hours; cost = kWh x unit rate

Worked example

With the default values below, Energy Consumption (kWh) Calculator returns Cost for the period of $37.80. Change any input above and every figure here is recalculated in your browser.

Inputs used

Appliance power
1,800 W
Hours used per day
2.5 h/day
Electricity rate
0.28
Days in the period
30 days

Results

Cost for the period
$37.80
Energy used
135.00 kWh
Energy per day
4.50 kWh
Annualised cost
$459.90

Step by step

  1. 1Values used
  2. 2Energy and cost
  3. 3Cost for the period= 37.80
  4. 4Energy used= 135.00 kWh
  5. 5Energy per day= 4.50 kWh
  6. 6Annualised cost= 459.90

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Does the nameplate wattage equal actual draw?

Rarely. Motors, fridges and anything thermostatically controlled cycle on and off, so actual consumption is often 30-60% of nameplate times hours.

What about standing charges?

They are fixed daily amounts independent of consumption, so add them separately rather than into the unit rate.

Related Calculators

Energy Consumption (kWh) Calculator | Calcrivo