Electricity Cost Calculator

An electricity cost calculator estimates what it costs to run a household appliance from its wattage, daily usage, and the local electricity rate. Each appliance's wattage is multiplied by its daily hours of use and by the number of days in the billing period, then divided by 1,000 to convert watt-hours into kilowatt-hours. That kWh figure is multiplied by the electricity rate to produce the estimated cost, for each appliance individually and for all appliances combined.

• Each appliance entry carries a name, its wattage rating (W), and how many hours per day it runs. Numeric fields accept decimals, fractions such as 3/4, and mixed numbers such as 1 1/2; commas and dollar signs are stripped automatically.
• Settings holds the electricity rate per kWh (default 0.12), a currency symbol for regions that do not use dollars, and the number of days per month to match a specific billing cycle length.
• Results show each appliance's monthly kWh consumption and cost, followed by totals for the month and the year.
• A step-by-step view, available in Settings, shows the formula substitution for every appliance: wattage multiplied by hours per day multiplied by days per month, divided by 1,000, equals kWh; kWh multiplied by rate equals cost.

The core formula is: kWh per month = (Wattage x Hours per Day x Days per Month) / 1,000. Monthly cost = kWh per month x Rate per kWh. Yearly cost = Monthly cost x 12.

A 100 W device run 5 hours a day over a 30-day billing period draws (100 x 5 x 30) / 1,000 = 15 kWh that month. At the default rate of $0.12 per kWh, that is 15 x 0.12 = $1.80 for the month, or 1.80 x 12 = $21.60 across a year.

Tracking electricity consumption at the appliance level reveals which devices contribute most to utility bills and where changes in usage habits or equipment upgrades yield the largest savings.

• Household budgeting: List every major appliance in a home, from a 1,500 W space heater running 8 hours a day to a 60 W light bulb on for 12 hours, and compare their individual contributions to the monthly bill.
• Rental cost splitting: Tenants sharing a unit can enter their personal devices, such as a 200 W desktop computer used 10 hours a day, to estimate each person's fair share of the electricity bill.
• Appliance replacement decisions: Compare the annual operating cost of an older 800 W refrigerator running 24 hours against a newer 350 W model to quantify the payback period on the upgrade.
• Small business overhead: A shop owner can enter equipment like a 2,000 W commercial oven running 6 hours and a 150 W POS system running 14 hours to forecast monthly utility expenses for pricing decisions.
• Seasonal planning: Adjust hours per day for seasonal appliances, such as an air conditioner at 1,200 W for 10 hours in summer versus 0 hours in winter, to project costs across different months.
• Solar offset analysis: After calculating total monthly kWh, compare the figure against a solar panel system's expected output to determine what percentage of consumption the panels would cover.