The useful answerFor an appliance estimate, use the charges that rise with each additional kWh. A price of 18 cents per kWh is entered as $0.18, not $18.

Find the usage and the billing period

Look for electricity consumption measured in kilowatt-hours, usually abbreviated kWh. Note the start and end dates too. A 35-day bill will not compare directly with a 28-day bill, even if your daily habits are similar.

For a fair first comparison, divide each period’s kWh by its number of days. A 420 kWh bill over 30 days equals 14 kWh per day. A 448 kWh bill over 32 days also equals 14 kWh per day.

Separate variable and fixed charges

Electricity bills can distinguish supply, delivery and other charges. The EIA explains that rates may apply to individual services, and that the supplier and delivery utility may differ. Look at which line items are priced per kWh and which are charged once per billing period.

Illustrative bill: supply costs 10¢/kWh, variable delivery costs 7¢/kWh and another usage charge costs 1¢/kWh. The combined variable rate is 18¢/kWh, or $0.18. A separate $12 monthly account fee does not disappear when you use an appliance less.

Follow a sample bill from line items to calculator input

Constructed example: 500 kWh, before taxes or adjustments
Line itemUnit priceAmount
Supply$0.10/kWh$50
Variable delivery$0.07/kWh$35
Other usage charge$0.01/kWh$5
Fixed account fee$12 per billing period$12
Total current charges$102

Add the three usage prices: $0.10 + $0.07 + $0.01 = $0.18/kWh. Enter 0.18 in the calculator, not 18 and not the $102 total. In this flat-rate example, avoiding 10 kWh reduces the usage charges by $1.80; the $12 fee remains.

Do not add the supply charge twice if you pay a separate supplier and the utility statement already includes that same amount. A line in cents must be divided by 100 to become dollars. For an unclear adjustment, check whether it varies with kWh before treating it as part of the appliance rate.

Why total bill divided by kWh can mislead

Suppose 500 kWh costs $90 in variable charges plus a $12 fixed fee. The total is $102. Dividing $102 by 500 gives $0.204/kWh: an average all-in bill cost, not the $0.18 price of an additional kWh in this example.

Both figures answer legitimate questions. Use the all-in average to summarize a bill. Use the relevant variable rate to estimate how an appliance changes that bill. Taxes, credits and tiered rates can make the calculation more involved; ask the utility to explain unclear items.

Handle time-of-use prices separately

If a device uses 2 kWh at $0.12 and another 3 kWh at $0.30, the daily cost is $0.24 + $0.90 = $1.14. The usage-weighted rate is $1.14 ÷ 5 = $0.228/kWh. A simple unweighted average of the two rates would give a different result.

Our calculator accepts a single rate. Run separate scenarios for each time band, or use a properly weighted rate for the consumption you expect. State averages are useful background, but your own current tariff is the better input.

Keep a reusable record

Save the tariff name, effective date and the line items included in your chosen rate. The ledger below keeps current charges separate from payments. For tiered plans, calculate the before-and-after bill using the tiered-rate example; a single average can misprice the next kWh.

Electricity bill and payment ledger

A free CSV to use in a spreadsheet app. Fill in your own copy; it contains no automatic formulas and does not upload your bills or readings.

Download electricity bill and payment ledger (CSV)

Choose your next step

Continue with the question that matches your next decision:

Sources & further reading

Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.