Appliance Electricity Cost Calculator
Calculate daily, monthly and annual electricity costs for several appliances. Include standby power, quantities and a comparison electricity tariff.
Your inputs
Example inputs are hypothetical. Choose units and assumptions that match your measurements.
Your result
Enter your values, then choose Calculate.
Calculations stay in this browser. Display rounding does not change the underlying calculation.
Calculation breakdown
Method, assumptions and worked example
Calculate appliance running costs
Daily kWh = quantity × [active watts × active hours + standby watts × (24 − active hours)] ÷ 1,000. Multiply kWh by your electricity price to estimate the variable energy charge. This tool uses 30 days for a month and 365 days for a year.
Worked example
A 100 W appliance used for 5 hours daily with 2 W standby for the other 19 hours uses (100 × 5 + 2 × 19) ÷ 1,000 = 0.538 kWh/day. At 0.25/kWh it costs 0.1345 daily, 4.035 over 30 days and 49.0925 over 365 days. A 0.20 tariff would cost 39.274 annually, a difference of 9.8185 before display rounding.
Use average power for cycling appliances
A refrigerator or air conditioner does not necessarily draw its rated maximum all day. Use measured average active watts or derive consumption from a reliable energy label. For example, a measured 1.2 kWh over 24 hours corresponds to 50 average watts over 24 hours with zero separate standby. Do not count both that total and separate cycling or standby energy.
Compare rates without overstating savings
Enter the same appliance schedule at both rates. A positive tariff difference means the comparison rate has a lower variable energy cost. Fixed daily charges, tariff bands, demand charges and taxes absent from the entered rate are excluded. Seasonal usage changes need separate scenarios. Your complete electricity bill can therefore differ from this appliance estimate.
Frequently asked questions
Can I add several appliances?
Yes. Add a row per appliance type and use quantity for identical units with the same usage.
Is standby counted while the appliance is active?
No. Standby is applied only to the remaining hours of the 24-hour day.
Can I use this for an EV?
For a simple measured wall-power schedule, yes. The EV tool additionally handles charging losses, tariffs and battery state of charge.
Method review and references
Formula and content reviewed on 10 October 2026. Worked examples are hypothetical. Methods and assumptions are explained on each page. Use actual measurements, product yields and applicable school or employment rules. These tools are independent estimates.
The calculation or selection method is described above. Use the relevant school policy, supplier quote or measurement definition when choosing inputs.