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Electricity cost calculator

Energy cost = watts × hours per day × days × price per kWh ÷ 1000.

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Answer

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Energy cost = watts × hours per day × days × price per kWh ÷ 1000.

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Precision and calculation record
Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.
Step-by-step calculation
Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.
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    Save the current answer, then change an input to compare. This clears when you leave.
    Formula and assumptions
    Assumes constant power while running. Use measured average power for cycling appliances. Fixed charges and changing tariffs are excluded.
    Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.
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    Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.
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    Updated 
    Using Electricity cost calculator
    Energy cost = watts × hours per day × days × price per kWh ÷ 1000.
    Assumes constant power while running. Use measured average power for cycling appliances. Fixed charges and changing tariffs are excluded.
    Next: Capacitance to charge calculator
    A worked example
    With power (watts) = 100, hours per day = 5, price per kwh = 0.2, days = 30, the energy cost is 3.
    Next: Battery life calculator
    Next: Electric vehicle fuel savings calculator
    Before you use the result
    Assumes constant power while running. Use measured average power for cycling appliances. Fixed charges and changing tariffs are excluded.
    Example results for power (watts)
    These examples use Hours per day: 5; Price per kWh: 0.2; Days: 30. They are reference calculations, not recommended settings.
    Power (watts)Energy cost
    501.5
    1003
    2006
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    ToolOctopus. “Electricity cost calculator.” Updated 2026-09-26. https://tooloctopus.com/electricity-cost-calculator.
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