Electricity Usage Calculator Formula

Understand the math behind the electricity usage calculator. Each variable explained with a worked example.

Use the Electricity Usage Calculator

Formulas Used

Monthly Electricity Bill

monthly_bill = monthly_cost

Annual Electricity Cost

annual_cost = monthly_cost * 12

Daily Cost

daily_cost = monthly_cost / 30

Annual Consumption

annual_kwh = monthly_kwh * 12

Variables

VariableDescriptionDefault
monthly_kwhMonthly Electricity Use(kWh)900
rate_per_kwhElectricity Rate(USD/kWh)0.15
fixed_chargeMonthly Fixed Charge(USD)12
monthly_costDerived value= monthly_kwh * rate_per_kwh + fixed_chargecalculated

How It Works

How to Calculate Electricity Cost

Your electricity bill is based on energy consumed (kWh) multiplied by the utility rate, plus fixed charges.

Formula

Monthly Bill = (kWh * Rate per kWh) + Fixed Charge

Average US Rates

  • National average: ~$0.15/kWh
  • Cheapest states: $0.08-0.10/kWh (Louisiana, Oklahoma)
  • Most expensive: $0.25-0.35/kWh (Hawaii, Connecticut)

    • Worked Example

    A home using 900 kWh/month at $0.15/kWh with a $12 monthly fixed charge.

    monthly_kwh = 900rate_per_kwh = 0.15fixed_charge = 12
    1. 01Usage charge: 900 * $0.15 = $135.00
    2. 02Monthly bill: $135.00 + $12.00 = $147.00
    3. 03Annual cost: $147.00 * 12 = $1,764
    4. 04Daily cost: $147.00 / 30 = $4.90

    Frequently Asked Questions

    What is a kWh?

    A kilowatt-hour (kWh) is a unit of energy equal to using 1,000 watts for one hour. For example, a 100-watt light bulb running for 10 hours uses 1 kWh.

    What is the average monthly electricity usage?

    The average US household uses about 886 kWh per month, though this varies widely by region, home size, and climate.

    How can I reduce my electricity bill?

    Switch to LED bulbs, upgrade to efficient appliances, use a programmable thermostat, seal air leaks, and run heavy appliances during off-peak hours.

    Ready to run the numbers?

    Open Electricity Usage Calculator