How to use
- Enter each appliance’s rated power in watts or kilowatts.
- Enter daily run time and quantity, then set the exact number of days you want to estimate.
- Enter the price shown on your tariff per kilowatt-hour. The currency symbol is only a label; no conversion occurs.
- Select Calculate. Edit any input to discard the old result; Clear removes values but keeps unit choices.
Formula
For each row: energy (kWh) = power (kW) × hours per day × quantity × days. Watts are divided by 1,000 first.
Cost = total energy × your price per kWh. Calculations retain full precision; ordinary displayed values use at most two decimal places.
Examples
Desk setup
A 120 W setup used 8 hours a day for 20 days uses 19.2 kWh. At 0.20 per kWh, it costs 3.84.
Two lamps
Two 10 W lamps used 5 hours daily for 30 days use 3 kWh. Add other rows to include more devices in the same stated period.
Limits
- This is a straight energy estimate, not a utility bill forecast. Tiered rates, fixed fees, taxes, demand charges, standby use, and changing power draw are excluded.
- Use a period that matches your goal. The calculator does not silently convert a daily estimate into a month or year.
- Rated power may differ from measured consumption. For variable-load equipment, use a measured or representative average.
- This tool does not recommend wiring, appliance sizing, tariffs, or local electricity suppliers.
Frequently asked questions
What is the difference between kW and kWh?
kW is power at a moment; kWh is energy accumulated over time. A 1 kW device running for 2 hours uses 2 kWh.
Can I use any currency?
Yes. Enter the numeric price per kWh and read the result in that same currency. No exchange-rate conversion is performed.
Why is my bill different?
Bills can include fixed charges, taxes, tiered prices, time-of-use rates, and other consumption not entered here.
Can I add several appliances?
Yes, up to six rows in one calculation, all using the same number of days and price per kWh.