Electricity Cost Calculator
Calculate an appliance's energy use in kWh and its electricity cost per day, month and year from its wattage, hours of use, days per week and price per kWh.
Results
- kWh per day = watts × hours × quantity ÷ 1000. A year has 365 days scaled by days used per week; a month is one twelfth of a year.
What is Electricity Cost Calculator?
Converts an appliance's power rating and usage into energy (kWh) and cost per day of use, per month and per year. You can account for several identical devices and for use on only some days of the week.
How to use Electricity Cost Calculator
- Enter the Power in W or kW (from the label or a power meter).
- Enter the Hours used per day and Days per week.
- Enter the Price per kWh and the Number of devices.
Example
100 W, 5 h/day, 7 days/week, 0.20 per kWh
3.04 per month (15.21 kWh); 0.10 per day; 36.50 per year
When to use Electricity Cost Calculator
Use it to compare appliances, estimate the cost of a heater or a PC, or check a bill. Many devices draw less than their rated power on average (fridges cycle, TVs vary), so a plug-in meter gives the most accurate wattage. Tiered or time-of-use tariffs are not modelled.
How Electricity Cost Calculator works
kWh per day = watts × hours × quantity ÷ 1000. Yearly kWh = daily kWh × days per week × 365 ÷ 7, and a month is one twelfth of a year (about 30.4 days). Each cost = kWh × price per kWh.
Common Use Cases
- Estimating the cost of running a space heater
- Comparing an old and a new fridge
- Calculating a gaming PC's yearly energy cost
- Checking standby consumption
FAQs
How do I convert amps to watts?
Watts = volts × amps, for example 230 V × 2 A = 460 W.
Why use 365 ÷ 12 days per month?
It averages months of different lengths, so twelve months add up exactly to one year.
Does it handle standby power?
Yes, enter the standby wattage and the hours it spends in standby.