Work out energy consumption (kwh) instantly with clear inputs, formula shown and shareable results.
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.
Energy and cost
kWh = watts / 1000 x hours; cost = kWh x unit rate
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.
Rarely. Motors, fridges and anything thermostatically controlled cycle on and off, so actual consumption is often 30-60% of nameplate times hours.
They are fixed daily amounts independent of consumption, so add them separately rather than into the unit rate.