Home Energy Use Calculator

Estimate your home’s daily, monthly and annual electricity use and cost from a list of appliances and their run times. Calculates in your browser.

Write numbers without thousands separators (1500, not 1,500), or separate the fields with semicolons.

Monthly cost

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Daily use-
Monthly use-
Annual use-
Annual cost-

Show the math

Each appliance's daily energy is its power times the hours it runs:

daily kWh = Σ (watts × hours × qty) ÷ 1000

cost = kWh × rate

A month is treated as 30 days and a year as 365 days. Quantity defaults to 1 if left off. All math runs in your browser.

What this does

A home energy use calculator estimates your daily, monthly, and annual electricity use and cost from a list of appliances and their run times.

How to use it

  1. List each appliance and its watts.
  2. Add hours run and quantity.
  3. Enter your electricity rate.
  4. Read the kWh and cost totals.

How it works

A month is treated as 30 days and a year as 365 days. Cost is total energy times your per-kWh rate.

kWh = watts × hours × qty ÷ 1000

Understanding your result

The total is an estimate from the run-times you enter, and its real value is showing which appliances dominate. A handful of high-wattage, long-running loads, heating, cooling, water heating, usually account for most of the bill, so target those for savings rather than fretting over low-watt devices that barely move the total.

Example

A 1,000 W heater run 4 hours a day uses about 120 kWh a month.

Last updated .

Frequently asked questions

How is appliance energy calculated?

Each appliance’s daily energy is its watts × hours run × quantity, divided by 1000 for kWh. Cost is energy × your rate.

How are months and years counted?

A month is treated as 30 days and a year as 365 days for the totals.

Is my data stored?

No. Everything is calculated locally in your browser.