Estimate appliance electricity use and cost from user-entered power, running time, recurrence, and price per kilowatt-hour. Compare multiple appliances, calculate from known energy, or work backward from a budget.
Convert appliance power to kilowatts, multiply by hours of use to find kilowatt-hours, then multiply by your electricity price per kWh.
Recurring projections annualize the entered use convention without rounding individual appliances before totals are added.
power kW = power W ÷ 1,000energy kWh = power kW × duty cycle × hours × quantitycost = energy kWh × user-entered price per kWhdaily × 365; weekly × 52; monthly × 12; annual uses as enteredstandby kWh/day = standby W ÷ 1,000 × standby hours/day × quantityavailable kWh = budget ÷ price per kWh; runtime hours = available kWh ÷ appliance kWA 1,500 W appliance used for 2 hours consumes 3 kWh. At $0.20/kWh it costs $0.60 per use.
A 100 W device used 8 hours daily consumes 0.8 kWh/day and 292 kWh/year, costing $58.40/year at $0.20/kWh.
A continuous 50 W load consumes 1.2 kWh/day and 438 kWh/year.
Known usage of 450 kWh/month costs $81/month at $0.18/kWh, before any separately entered fixed charge.
Ten 10 W bulbs used 5 hours daily consume 0.5 kWh/day and cost $0.10/day at $0.20/kWh.
A 1,500 W appliance at a 50% duty cycle for 2 hours uses 1.5 kWh and costs $0.30 at $0.20/kWh.
A $100 budget at $0.20/kWh provides a theoretical 500 kWh.
Use the price that applies to your bill or scenario; CalcRocket does not look up utility rates.
Nameplate power may differ from actual draw, especially for devices that cycle or vary output.
Known-energy mode shows optional monthly or annual fixed charges separately from energy charges.
Watts and kilowatts measure power. A kilowatt-hour measures energy: one kilowatt used for one hour.
Appliance mode reports active-hour and per-use cost. Recurring values use 365 days, 52 weeks, and annual divided by 12 for an average month.
Each included row is calculated independently at full precision. Annual kWh values are summed before cost and share-of-listed-use percentages are calculated.
Standby hours are entered explicitly. Duty cycle reduces effective active power but is never guessed. For daily use, active and standby hours cannot exceed 24.
Known-energy mode converts Wh or kWh through the shared energy converter. Reverse mode divides a budget by a positive entered rate and optionally estimates runtime from entered appliance power.
Cycling, controls, load, temperature, efficiency, tariff structure, taxes, grid fees, and actual power draw can make a real bill differ from this arithmetic estimate.
Multiply kilowatt-hours by your applicable price per kWh.
Convert power to kW, multiply by running hours, then multiply by your entered rate.
Divide watts by 1,000 and multiply by hours.
It is the energy used by one kilowatt of power for one hour.
A 1,500 W load is 1.5 kW, so hourly cost is 1.5 multiplied by your rate.
Multiply energy per use by daily uses and add explicitly entered standby energy.
For recurring estimates, CalcRocket divides annual cost by 12.
Annualize the entered recurrence and multiply annual kWh by your rate.
It uses 0.1 kWh per hour at 100% duty; multiply that by your price per kWh.
Multiply standby kW by standby hours per day and quantity.
It is your estimate of the percentage of the usage period that the device draws the entered power.
Yes. Add up to 20 rows and include or exclude each from the total.
Yes. Enter Wh or kWh, its period, and your rate.
Reverse mode divides the budget by a positive price per kWh.
No. You must enter the rate applicable to your situation.
Actual draw, cycling, tariff tiers, time-of-use pricing, taxes, fees, and fixed charges can differ from the inputs.