Where Our Data Comes From
Updated August 14, 2026
Every number on this site derives from official U.S. Energy Information Administration (EIA) data. This page names the exact series, the formula, the units, the publication lag, and the refresh schedule for each. Nothing is projected, modeled, or borrowed from third-party estimates.
Electricity rates and bills
| Number | Formula | Source series | Lag |
|---|---|---|---|
| Average rate (¢/kWh) | residential revenue ÷ residential sales | EIA API v2, electricity/retail-sales, monthly, residential sector (the series behind Electric Power Monthly Table 5.6.a) | ~2 months |
| Average bill ($/month) | residential revenue ÷ residential customer count | ||
| Average usage (kWh/month) | residential sales ÷ residential customer count |
Utility-level rates and the ZIP lookup
| Number | Formula / source | Lag / vintage |
|---|---|---|
| Utility average rate and bill | Same formulas as above, per utility and state, from EIA Form 861-M (monthly sales to ultimate customers, residential). Months failing sanity screens (implied rate under 2¢ or over 75¢/kWh, bill under $10 or over $1,200, sales without customers) are excluded from display. | ~2 months |
| ZIP → utility mapping | NREL/OpenEI, "U.S. Electric Utility Companies and Rates: Look-up by Zip Code (2024)", CC BY 4.0. We use only the ZIP-utility assignment, never its rate columns. | 2024 vintage, updated when NREL publishes |
EIA's monthly survey covers utilities above a size cutoff (roughly 700 utility-state records per month); smaller utilities report only in the annual EIA-861 census and appear in the ZIP lookup by name without monthly numbers.
Gasoline prices by state
| Number | Source | Cadence |
|---|---|---|
| State pump prices (regular, diesel) | AAA state averages. No government source publishes daily pump prices for all 50 states (EIA's weekly survey covers ~10); AAA is the industry-standard series that EIA itself cites. | Weekly refresh of AAA's daily figure |
| State fuel taxes and fees | Tax Foundation total state gasoline taxes/fees, plus the 18.4¢ federal excise | Annual |
| Crude-oil component | EIA WTI Cushing spot, monthly average ÷ 42 gal/bbl | Monthly |
| U.S. weekly average pump price (the “why are gas prices high” page) | EIA Gasoline and Diesel Fuel Update, U.S. regular all-formulations retail price, weekly since 2020. Component shares (crude, refining, distribution and marketing, taxes) are EIA's published breakdown, dated on the page | Weekly (Mon) |
| Crude and gasoline price projections | EIA Short-Term Energy Outlook annual series (WTI, Brent, U.S. retail regular), pulled from the EIA API so the page cannot quote a superseded edition. Always labeled as EIA's projection; we publish no forecast of our own | Monthly (~2nd Tuesday) |
| Refining, distribution & margins | Computed residual: pump price − crude − taxes. Includes fuel-specification and carbon-program costs embedded in prices rather than levied as taxes. | — |
Home heating costs
| Number | Source / formula | Cadence |
|---|---|---|
| Delivered heat cost ($/MMBtu) | fuel price ÷ (heat content per unit × equipment efficiency), so every fuel is on one scale. Heat-content factors from EIA (gas 1.037 MMBtu/Mcf, oil 0.1385/gal, propane 0.0915/gal, electricity 0.003412/kWh); standard equipment efficiencies (gas furnace 92% AFUE, oil 86%, electric resistance 100%, heat pump COP 2.8) consistent with ENERGY STAR furnace and heat pump criteria and DOE Energy Saver guidance. | — |
| Natural gas price by state | EIA residential price ($/Mcf; 1 Mcf ≈ 10.37 therms) | Monthly |
| Heating oil & propane by state | EIA weekly residential survey (~21 states for oil, ~38 for propane), published October–March | Weekly, in season |
| Heat pump payback and incentive status | Running-cost savings are computed from the same season averages as the rows above. We publish no installed-cost estimate: quotes vary too much by home for a national average to be meaningful, so the calculator uses the reader's own quote. Federal credit status is cited to the IRS; state rebate status is deliberately not duplicated here and links to the Department of Energy, because program availability changes week to week and a stale table would mislead | With the heating data |
| Electricity by state | our EIA residential rate series (see above) | Monthly |
Prices shown are the most recent complete heating-season (October–March) average for each fuel, so summer and winter builds report the same season until a new one finishes. The calculator's heating load and heat-pump COP are user-adjustable; we do not model home climate, insulation, or time-of-use rates.
Solar payback
| Number | Source / formula | Cadence |
|---|---|---|
| Value of a kWh of solar output | the state's residential electricity rate (see above), on the basis that a kWh generated is a kWh not bought. Assumes full retail net metering; under net billing, exports are credited below retail and the value is lower | Monthly |
| Payback | quote ÷ (annual production × rate). We publish no system-cost estimate and no production model: roof orientation, tilt, and shading decide output, and every quote already states an estimated annual production, so the calculator uses the reader's own numbers. Simple payback, no financing, no rate escalation | With the rate data |
| Credit and incentive status | Federal 25D status cited to the IRS. State, utility, and net-metering rules are not reproduced here and link to DSIRE, which maintains them | Linked, not mirrored |
EV vs. gas comparison
| Number | Source / formula | Cadence |
|---|---|---|
| EV cost per mile | state residential electricity rate ($/kWh, EIA) ÷ EV efficiency. Default 3.3 mi/kWh (~30 kWh/100 mi, fueleconomy.gov). | Electricity monthly |
| Gas cost per mile | state pump price ($/gal, AAA) ÷ fuel economy. Default 27 MPG (MY2024 new-vehicle real-world average 27.2 MPG, EPA). | Gasoline weekly |
| Annual saving | per-mile gap × miles driven. Default 13,500 mi/yr (FHWA average per driver). | — |
All three defaults are user-adjustable on the page. The comparison is fuel cost only (no purchase price, depreciation, insurance, or maintenance), and home charging is priced at the average residential rate rather than a time-of-use EV tariff.
National energy totals (U.S. Energy Facts)
| Number | Source | Cadence |
|---|---|---|
| Production, consumption, trade, energy by source, CO2 | EIA Monthly Energy Review annual
series, by MSN code. Trillion Btu converted to quads (÷1,000). Note for maintainers:
TETCEUS is total energy-related CO2; TEACBUS looks like a CO2
series but returns trillion Btu of transportation energy |
Annual, revised through the year |
| Electricity generation by source | EIA electric power operational data, U.S., all sectors. The published mix is utility-scale: it reconciles to the all-fuels total using utility-scale solar plus a bucket for geothermal, biomass, petroleum and other. Small-scale solar is stated separately rather than folded in, because the all-fuels total excludes it | Annual and monthly |
| Renewable sources | Always published component by component (biomass, wind, solar, hydroelectric, geothermal). A combined renewables figure alone would hide that these behave very differently | With the annual series |
Each figure on that page carries its own "data through" label rather than a single page-wide date, because the annual totals, the generation series, and the weekly and monthly price series publish on different schedules.
World prices
| Number | Source | Cadence |
|---|---|---|
| European household electricity / gas prices | Eurostat nrg_pc_204 (electricity, band DC: 2,500–4,999 kWh/yr) and nrg_pc_202 (gas, band D2: 20–199 GJ/yr), all taxes and levies included, CC BY 4.0 | Half-yearly |
| European pump prices (gasoline, diesel) | European Commission Weekly Oil Bulletin, prices with taxes as reported by member states | Weekly (Mon) |
| U.S. comparators on world pages | EIA: our state electricity series averaged over the same semester; residential natural gas (consumption-weighted, 1 Mcf ≈ 303.9 kWh); weekly retail gasoline (regular) and on-highway diesel | Matches the European series |
| UK pump prices (petrol, diesel) | DESNZ weekly road fuel prices, ULSP and ULSD pump prices in pence per litre. The UK left the Weekly Oil Bulletin after Brexit, so it comes direct from DESNZ | Weekly |
| Canadian pump prices (gasoline) | Statistics Canada table 18-10-0001, monthly average regular unleaded at self-service stations, cents per litre. Gasoline only. At the newest month Statistics Canada publishes a Canada-wide figure for regular gasoline alone and reports diesel and heating fuel for individual surveyed cities; averaging those cities would produce a national number the agency does not publish, so we leave Canadian diesel blank | Monthly |
| Japanese pump prices (gasoline, diesel) | METI / Agency for Natural Resources and Energy petroleum retail survey, national average cash price for regular gasoline and diesel, consumption tax included, yen per litre | Weekly |
| Brazilian pump prices (gasoline, diesel) | ANP Levantamento de Preços, national average resale price for common gasoline and S500 diesel, reais per litre | Weekly |
| Indian pump prices (petrol, diesel) | PPAC retail selling prices, rupees per litre. Shown as New Delhi, not as a national average. State sales tax on fuel varies widely across India and PPAC publishes retail prices city by city rather than as one country figure; Delhi is among the cheaper large cities, so an India-wide average would be higher | Per published date |
| Currency conversion | ECB reference rates: semester average USD/EUR for electricity and gas; for fuels, the rate on each row's own date, cross-converted through the euro (GBP, CAD, JPY, BRL, INR) | Daily |
Comparability caveats are stated on each world page (consumption bands differ from U.S. usage; Euro-super 95 vs U.S. regular octane conventions; national averages throughout, except India as noted).
Every country in the pump-price table is taken from the agency that collects the price in that country. No third-party price compilation is used, and because the sources publish on different schedules, each row on that page carries its own date rather than sharing one week-wide heading.
World energy mix, production and environment
| Number | Source | Cadence |
|---|---|---|
| Energy mix, fossil-fuel share, electricity generation, oil/gas/coal production | Energy Institute Statistical Review of World Energy (successor to the BP Statistical Review), annual series back to 1965. Fossil share = (oil + gas + coal) ÷ total primary energy, on the input-energy (substitution) accounting used in the Statistical Review. Renewables already include hydro, wind, solar and biofuels | Annual (published each June) |
| Flaring and methane emissions per barrel produced | Statistical Review gas-flaring and process-methane series, combined in CO2-equivalent at 80× CO2 on a 20-year basis as reported, divided by fossil production in barrels of oil-equivalent | Annual |
| Air pollutants (SO2, NOx, PM2.5), CO2 per person, HDI | Yale Environmental Performance Index 2024 raw indicator files, joined to Statistical Review energy by country | Biennial |
These annual figures refresh once a year when the Statistical Review publishes, not on the monthly electricity cycle. Every world energy page states its data year on the page. Country pages are keyed to ISO3 codes so their URLs stay stable when display names change.
What these numbers are, and are not
- They are average effective prices. Revenue divided by sales includes every charge on the bill: energy, delivery, fixed charges, riders, taxes collected through rates. Research on consumer behavior (Ito 2014, American Economic Review) finds households respond to average price, which is why we lead with it.
- They are not tariff prices. Your marginal rate, your utility's fixed charge, and time-of-use differentials will differ from the state average.
- They are official reported data with some estimation. EIA's monthly figures come from Form EIA-861M, a survey of a sample of utilities with imputation for the rest; final census values arrive with the annual EIA-861. EIA revises recent months as final data lands. We re-fetch monthly and log every revision on the data updates page.
Publication lag, disclosed
EIA publishes monthly retail data roughly two months after the fact, typically in the Electric Power Monthly around the 25th. Every page on this site states the actual data month ("Data through May 2026"). We do not project or nowcast unpublished months; a disclosed lag beats undisclosed modeling.
Refresh schedule
The pipeline re-fetches the full EIA series and rebuilds this site monthly, after the Electric Power Monthly release. The "Updated" date on each page is a real data refresh, never a re-dating.
Revisions policy
When EIA revises a previously published value, we adopt the revision and record it (date observed, series, month, old value, new value) in a public log. History is never silently restated: see data updates.
Related resources
EIA's own Electricity Data Browser is the canonical source for this data. The Heatmap-MIT Electricity Price Hub is a complementary project that builds tariff-based estimates with component breakdowns; we link it as a resource, and none of our numbers derive from it.