Electricity Cost Calculator

What is an Electricity Cost Calculator?

An electricity cost calculator turns three everyday numbers — how much power a device draws, how long it runs each day, and what you pay for electricity — into the energy it consumes and the money it costs over a day, a month and a year. It is the quickest way to budget your power bill, decide whether an old appliance is worth replacing, or compare the running cost of two devices side by side. Electricity is sold in kilowatt-hours (kWh): one kilowatt-hour is the energy used by a 1000-watt device running for one hour. Because every appliance is labelled with a power rating — in watts (W) or kilowatts (kW) — you can estimate its cost without any special meter. Enter the wattage, the hours per day, and your price per kWh, and the calculator does the rest. You can add up to three appliances to compare them or to estimate a whole room. The cost is left currency-neutral — you supply the price and an optional label — so it works just as well for a fridge in Tokyo as a heater in Berlin.

How to use this calculator

1. Enter the appliance's power and pick the unit — watts (W) for most household devices, or kilowatts (kW) for large ones. 2. Enter how many hours per day it runs. 3. Optionally set the quantity if you have several identical units. 4. Enter your price per kWh from your electricity bill, and the days per month to bill (30 by default). 5. Add a currency label if you want totals to read like '12 USD'. 6. Toggle the CO₂ estimate to see the approximate carbon footprint. Use 'Add appliance' to compare up to three devices; the headline figure is the combined monthly cost.

Formula & Worked Example

The energy and cost come from the defining relationship between power, time and energy: kWh = power (kW) × hours— watts are divided by 1000 to get kilowatts Daily kWh = kW × hours per day × quantity Monthly kWh = daily kWh × days per month Yearly kWh = daily kWh × 365 Cost = kWh × price per kWh For example, a 1000 W (1 kW) heater run 3 hours a day for a 30-day month uses 1 × 3 × 30 = 90 kWh; at a price of 30 per kWh that is 2,700. A 1.2 kW device run 2 hours a day uses 2.4 kWh per day, costing 60 at a price of 25. A 60 W bulb left on 24 hours a day uses 60 ÷ 1000 × 24 × 30 = 43.2 kWh per month.

Interpreting Results

The monthly cost is your headline figure — the energy slice of your bill for running this device. The daily figure is handy for short-term decisions, while the yearly figure reveals the true long-run cost of always-on devices: a small constant draw, multiplied by 8,760 hours a year, can add up to far more than an occasional high-power burst. Compare two appliances by entering them side by side; the one with the lower yearly cost is usually the better buy even if it costs more upfront. Remember that fixed charges, taxes and tiered rates on your bill are not included here, and that devices which cycle on and off will use less than a constant-run estimate.

Frequently Asked Questions