Electricity cost calculator & bill insights
Know what costs what.
Find your next small win.
No sign-up. Just a little clarity.
The cost of comfort
1,500 W × 4 hours/day
$32.40estimated / month
Rate: $0.18/kWh · 30 days
Example, not a utility quote.
01 / The mellow math
Your inputs. A clearer picture.
02 / Your bill, decoded
Break down a bill. Then see what changed.
Copy the separate charges from your bill. Put usage-based supply and delivery in their own fields; put flat delivery fees under fixed charges. Don’t count the same charge twice. Initial values are an example.
This bill, in pieces
The change explained
Usage effect = change in kWh × the average of the two variable rates. Rate effect = change in variable rate × the average of the two kWh totals. Fixed charges, taxes and credits make up the remaining difference. Together the three effects equal the change in your total bill. If either bill has 0 kWh, we show the variable-charge difference without splitting it into usage and rate effects.
Variable rate means (supply + usage-based delivery) ÷ kWh. It is a bill-derived average, not necessarily your contract rate. Tiered or time-of-use usage changes can also change this average. This is a descriptive comparison, not proof of a tariff increase.
Your entries are processed locally. They are saved only if you choose “Save on this device.” Don’t save private bills on a shared device.
03 / Before you buy
Compare annual energy use, then include the purchase cost.
The energy-cost difference
less per year
Simple energy-cost payback. Excludes financing, maintenance, changing rates, rebates, resale value and differences in performance.
04 / Keep it local
Find your company’s public records. Confirm your exact plan on your bill.
Loading public data…
Utility/state matches identify candidate companies, not exact address-level service. A company’s listed plans may apply in a different part of its service area. Records are not verified live quotes.
Company and county records: EIA-861, reporting year 2025. Residential tariff structures: OpenEI Utility Rate Database. Records may be historical, incomplete or awaiting updates. An absent end date is not proof a plan is current.
OpenEI source · EIA source05 / Good to know
A little clarity, start to finish
BillMellow helps US households connect everyday appliance use to the numbers on an electric bill. Start with your own inputs, compare the result, and check the assumptions before making a change.
Enter average operating watts, hours per day, your variable price per kWh and the days used. The calculator converts power and time into energy, then into dollars. Use Whole home to add several appliances; it estimates the devices you enter, not every charge on your utility bill.
Learn how watts become kWh and costEnter two bills to compare usage, average variable cost and fixed charges, taxes and credits. Daily usage helps account for different billing periods. The change analysis describes the entered amounts; it cannot prove why your consumption or tariff changed.
Read the electric bill breakdown guideUse Shift & save to compare the same kWh at two rates. For a new appliance, compare annual kWh and purchase cost to estimate simple energy-cost payback. Neither tool promises savings or models every charge on a complex tariff.
Understand peak and off-peak ratesDivide watts by 1,000, multiply by operating hours to get kWh, then multiply by your variable price per kWh. A 1,500-watt device used for four hours at $0.18/kWh costs $1.08 in energy charges. All three inputs are illustrative.
Compare billing days, kWh per day, variable charges, fixed fees, taxes and credits. A longer service period, different time-of-use pattern or changed adjustments can affect the total. A bill comparison identifies differences; it does not establish their cause.
That gives an all-in average, including fixed charges. For the cost of additional appliance use, use the relevant variable per-kWh charges from your tariff. Time-of-use and tiered plans may require more than one rate.
No. The directory shows public EIA and OpenEI records that may be historical or incomplete. A company match does not establish address-level service or plan eligibility. Confirm the current plan, schedule and charges with your provider.
The comparison uses values you type and processes them in your browser. It does not require a bill upload. Entries are saved in this browser only when you choose Save on this device. Shared appliance-calculation URLs contain the inputs you choose to share.
The arithmetic works with your own watts, hours, kWh and dollar rates. The utility directory includes the 50 states and Washington, DC, but does not promise complete, current tariff coverage for every company or address.
Energy units: US Energy Information Administration. Methods, limitations and public tariff sources: BillMellow methodology.