Enter electricity use in kWh and a rate from your bill, a planning estimate, or a past bill to calculate its cost.
Advanced options
Table of contents
How to use our kWh Cost Calculator
- Enter the amount to price in "Electricity used (kWh)." Copy it from a bill, appliance estimate, or project total.
- Choose "Rate source." Select "Enter an energy rate" to use a rate from your bill, "Use U.S. planning rate" for an editable estimate, or "Find rate from a bill" to calculate a rate from one bill.
- Fill in the fields for the selected source. For an entered rate, choose whether the number is in cents or dollars per kWh before entering it.
- Open "Advanced options" only when you need to add a fixed charge or percentage charge that is not already included in the rate.
- Select "Calculate." Check that "Rate used" has the expected unit and number; a rate calculated from a full bill is blended and can include more than the energy charge.
Definitions
kWh (kilowatt-hour): A unit of electrical energy. One kWh equals using 1,000 watts for one hour.
Electricity rate: The price for each kWh, commonly written in cents per kWh or dollars per kWh.
Energy cost: Electricity used in kWh multiplied by the rate per kWh. It does not automatically include fixed charges or taxes.
Blended effective rate: A whole electric bill divided by the kWh billed for that same period. It can include energy, delivery, fixed charges, taxes, and fees.
Fixed charge: A charge that does not change with electricity use, such as a customer or service charge.
U.S. planning rate: The editable 2026 residential estimate of 18.31 cents per kWh used for planning in this calculator. [1]
Common mistakes and quick fixes
Mistake: Entering 0.1831 while "Cents per kWh" is selected when the bill says $0.1831 per kWh.
Fix: Choose "Dollars per kWh," or enter 18.31 with "Cents per kWh" selected.
Mistake: Entering kW instead of kWh.
Fix: Enter kWh, which measures energy used. kW measures power and needs a time period before it can be turned into energy use.
Mistake: Using a bill total from one billing period and kWh from another.
Fix: Copy both values from the same bill so the calculated blended rate matches that period.
Mistake: Adding a customer charge or tax to a rate found from a whole bill.
Fix: Leave added charges blank with "Find rate from a bill" because the bill total may already include them.
Mistake: Typing 1,01 for money or using a comma as a decimal mark.
Fix: Use a decimal point for cents and commas only for thousands, such as $1,000.50.
Limitations & Key Assumptions / Boundary Conditions
- The energy-cost answer assumes one flat rate applies to every entered kWh.
- Time-of-use, seasonal, tiered, demand, and other utility pricing can produce a different bill total.
- A bill-derived rate is based on one bill period and may include delivery charges, fixed charges, taxes, and fees, so it is not necessarily an energy-only price.
- Optional fixed and percentage charges are added only with entered and planning rates. They are not added to a bill-derived rate to avoid possible double counting.
- The U.S. planning rate is a national residential estimate, not a local utility quote. Replace it with a current local rate when possible.
- This calculator needs kWh already known. Finding an appliance's kWh use may require its wattage and operating time.
Methodology
Cost calculation
The calculator converts the selected rate to cents per kWh before calculating. A rate entered in dollars is multiplied by 100. A rate from a bill is the total bill divided by billed kWh, then multiplied by 100.
rate (cents per kWh) = bill total ($) / billed kWh x 100
It multiplies the electricity used by the normalized rate and divides by 100 to calculate the energy cost in dollars.
energy cost ($) = electricity used (kWh) x rate (cents per kWh) / 100
Added charges
For entered and planning rates, an optional fixed charge is added to the energy cost. An optional percentage is then applied to that subtotal. A blank optional field adds nothing.
percentage charge ($) = (energy cost + fixed charge) x percentage / 100
estimated bill total ($) = energy cost + fixed charge + percentage charge
With "Find rate from a bill," added charges are not applied because the whole-bill rate may already include them.
Mini-example
For 500 kWh at 18.31 cents per kWh, the energy cost is $91.55. With a $12 fixed charge and a 5% added percentage, the percentage charge is $5.18 and the estimated bill total is $108.73 after rounding to cents.