kWh Cost Calculator
Find out what a single kilowatt-hour costs where you live, compare state and utility rates, and calculate the price of any amount of energy used.
Common conversions
| Input | Result |
|---|---|
| 500 kWh @ Idaho ($0.11/kWh) | $55.00 |
| 500 kWh @ Louisiana ($0.12/kWh) | $60.00 |
| 500 kWh @ Texas ($0.14/kWh) | $70.00 |
| 500 kWh @ US average ($0.16/kWh) | $80.00 |
| 500 kWh @ Illinois ($0.17/kWh) | $85.00 |
| 500 kWh @ New York ($0.22/kWh) | $110.00 |
| 500 kWh @ Massachusetts ($0.28/kWh) | $140.00 |
| 500 kWh @ California ($0.29/kWh) | $145.00 |
| 500 kWh @ Hawaii ($0.42/kWh) | $210.00 |
The math behind it
- $ = 18 × 0.42
Everything you need to know
What sets the price of a kilowatt-hour
The rate printed on your bill bundles three separate costs into one number: generation (fuel and power plant costs), transmission (moving power over long high-voltage lines), and distribution (the local wires and transformers that reach your house). In regulated states, a public utility commission approves the rate a monopoly utility can charge. In deregulated states like Texas and parts of the Northeast, you can pick a retail electricity supplier, and the generation portion of the rate becomes competitive while distribution stays fixed.
Why kWh rates vary so much by region
Idaho and Washington sit near $0.11/kWh because cheap hydroelectric power dominates their generation mix. Hawaii sits near $0.42/kWh because its isolated grid still burns imported oil for much of its generation and cannot import cheaper power from neighboring states. California's rate has climbed past $0.29/kWh partly from wildfire mitigation spending and grid modernization costs layered onto the bill. Population density, local fuel mix, and how much a utility has spent rebuilding its grid explain most of the 4x spread you see across the table above.
Marginal cost vs. your blended bill rate
The rate you enter here should be your marginal rate, the cost of the next kWh you use, not your blended rate (total bill divided by total kWh), which gets diluted by fixed fees. If your plan has tiers or time-of-use pricing, your marginal rate can be well above your blended rate once you cross a threshold or use power during a peak window. Use the marginal rate when deciding whether an extra appliance or an extra hour of use is worth the cost.
Common applications
Plug in the national average, your state's average, and your own bill's rate side by side to see how much of your cost comes from location rather than usage.
Annual production in kWh multiplied by the local rate gives your yearly offset. A system in Hawaii can pay back in 5 to 7 years; the same system in Idaho may take 15 or more.
Multiply your expected monthly kWh by the destination utility's published rate to budget before you sign a lease, rather than guessing from your old bill.
Price the same kWh amount at your flat rate and at the plan's peak and off-peak rates to see whether shifting usage would actually save money.
Common mistakes
That blended figure includes fixed charges and taxes. The marginal rate per additional kWh is what matters when deciding whether to run one more appliance.
Rates differ by up to 4x between states. Use your utility's actual published rate, not a national figure, for any budgeting decision.
A quoted rate might only apply to the first block of usage or to off-peak hours. Check the full rate schedule before comparing two plans on price alone.
Wattage is a rate of use; kWh is the total energy consumed. A 1,000 W device costs money only for the hours it actually runs, not for its wattage rating alone.
Frequently asked questions
What is the average cost of a kWh in the US?+
$0.16 per kWh is the national residential average in 2025, ranging from about $0.11 in Idaho to over $0.42 in Hawaii depending on the local generation mix and grid costs.
Is the price of a kWh the same everywhere in the US?+
No, rates vary roughly 4x across states. Cheap hydro power keeps Idaho and Washington under $0.12/kWh, while an isolated, oil-dependent grid keeps Hawaii above $0.40/kWh.
Why is electricity so expensive in Hawaii?+
Hawaii's grid is not connected to any other state, so it relies heavily on imported oil for generation instead of cheaper natural gas or hydro power available on the mainland.
Why is electricity cheap in Idaho and Washington?+
Abundant hydroelectric dams supply most of the generation in the Pacific Northwest, and hydro power has a low ongoing fuel cost compared to natural gas or oil plants.
Does a higher kWh rate always mean a higher bill?+
No, a low-usage household in an expensive state can still pay less than a high-usage household in a cheap state. Total cost is rate multiplied by kWh used, so both numbers matter.
What's the difference between marginal rate and blended rate?+
Marginal rate is what the next kWh costs you right now; blended rate is your total bill divided by total kWh, which is lower because it spreads fixed fees across all your usage.
Can I choose my own electricity rate or supplier?+
Yes, in about a dozen deregulated states including Texas, Pennsylvania, and Ohio, you can shop competing retail suppliers for the generation portion of your rate while the same utility still delivers the power.
How is the price of a kWh actually set?+
Generation, transmission, and distribution costs are added together, then a regulator approves the combined rate for regulated utilities, or competition sets the generation piece in deregulated markets.
Does the kWh rate change by season?+
Yes, many utilities charge higher summer rates to reflect peak air conditioning demand, sometimes 20 to 30 percent above the winter rate on the same plan.