Methodology: How the Utility Cost Estimate Works

1. Electricity

Price. For each state we take the latest 12 months of residential revenue and kWh sales from Form EIA-861M (August 2025 – July 2026) [1] and divide: price = Σ revenue ÷ Σ kWh. That is EIA’s own definition of average price, so it includes fixed customer charges, delivery, riders and taxes billed by the utility. Before using the file we recompute every monthly price from its revenue and sales and require it to match EIA’s published price to the cent; we also recompute calendar 2025 from the monthly rows and require it to match EIA’s published 2025 annual price for all 51 jurisdictions. Both checks pass for this release (Texas, for example: 15.47¢ for 2025).

Use. Typical monthly use = Σ kWh ÷ Σ customer-months over the same 12 months. Texas: 1,103 kWh. The typical bill is use × price, computed by the same engine as the calculator: 1,103 × 15.96¢ = $176.04.

Month by month. State pages chart revenue ÷ customers for each month — the average bill actually paid that month (Texas July 2026: $251.09). Months from 2025 onward are marked preliminary by EIA and can be revised.

Latest month. Electric Power Monthly Table 5.6.A [2] supplies the newest month and the same month a year earlier; our pipeline stops if it disagrees with the EIA-861M file. The final 2024 annual figures (Form EIA-861) [3] appear on state pages for comparison only.

2. Natural gas

Price. EIA’s annual average price of gas delivered to residential consumers, in dollars per thousand cubic feet [4]. We use 2025; for Connecticut, Maine, Maryland, North Carolina, Rhode Island, South Carolina EIA lists 2025 as not available (“NA”), so those states use 2024 and their pages say so.

Units. $ per therm = $ per Mcf ÷ (Btu per cubic foot ÷ 100), using the state’s heat content of gas delivered to consumers [7], the method in EIA’s conversion FAQ [8]. $ per ccf = $ per Mcf ÷ 10. The U.S. figure: $15.34 ÷ 10.36 = $1.481 per therm.

Use. Gas per customer = 2024 residential deliveries ÷ 2024 residential consumers [5][6] (2024 is the newest year with customer counts), converted to therms with the same heat content. The calculator divides by 12 for a monthly figure. The gas line starts switched on only where at least half of homes use natural gas in EIA’s RECS 2020 [11].

3. Heating oil and propane

Prices are EIA SHOPP residential prices for the week of March 30, 2026 [10][9], available for 21 states (oil) and 38 states (propane). They carry a “Dated price” label. Gallons default to RECS 2020’s average per household using the fuel in the state, where EIA published one. Cost per month = gallons a year × price ÷ 12.

4. “A home like mine”

Instead of the state average, you can describe one characteristic of your home: size band, number of people, main heating fuel or building type. The calculator then uses EIA’s RECS 2020 average consumption for that group in your census region (tables CE2.2–CE2.5) [12], while prices stay your state’s. Only one characteristic at a time is offered because EIA publishes one-way tables; combining them (say, size × heating fuel) would require us to invent an interaction we cannot source. We do not scale state averages by square footage or occupants for the same reason.

5. Arithmetic and rounding

• Electricity: kWh × ¢ ÷ 100. Gas: amount × price in the same unit. Oil/propane: gallons × price ÷ 12. Other bills: as entered.
• Defaults are shown rounded as published: kWh whole, ¢ to 2 decimals, gas to 0.1 unit and $0.001, gallons whole, $/gal to $0.001. The estimate is computed on exactly what the form shows, so the page’s worked example and your screen always agree.
• Each line is rounded to the cent (its annual figure is the unrounded monthly × 12, rounded), and totals are the sums of the rounded lines, so the breakdown always adds up to the total you see.
• Inputs are validated: negative numbers, non-numbers and implausible values (over 20,000 kWh a month, over 200¢ per kWh) are rejected with a message rather than silently clamped.

6. When data gets old

Each dataset has a date after which we stop pre-filling it. Past that date the calculator leaves the field empty and asks for your figure, instead of quietly showing a stale average. Our build tests fail 45 days before any of these dates unless the data has been refreshed.

7. Reading your estimate — and what it leaves out

The big number is the sum of every line that has all of its figures, per month; the annual figure adds each line’s month × 12. The gauge compares only your electricity line with the average residential customer in the state you picked: the tick at the top is that average, the right end is twice it. Labels on each line say where its figures came from: “EIA average” (state averages above), “Similar homes” (RECS 2020 regional averages), “Dated price” (last weekly heating-fuel price), “Your figure”, or “Needs your figure” when no verified number exists and the line is left out of the total until you add one.

Left out on purpose: deposits, connection and reconnection fees, equipment rental, late fees and budget-billing true-ups; any tax or rider your utility adds beyond what is already inside the average price; tiered and time-of-use pricing, which can move a bill either way; and the seasonal swing — a calculator month is an average month. A home that uses little electricity pays more per kWh than the average because the fixed customer charge is spread over fewer kWh.

8. What the estimate cannot know

Your utility’s tariff (fixed charge, tiers, time-of-use, local taxes), your thermostat and your weather. A state average blends every utility and plan in the state, so the same usage can cost noticeably more or less on your bill. That is why every field accepts your own number and labels which figures are yours and which are averages.

Snapshot generated October 5, 2026 by scripts/refresh-data.py from the raw EIA files, which are kept with the site’s source code.