Methodology: How This Site Tracks Propane Prices

PropanePricePerGallon.com is an independent vendor-neutral price tracker. Operator-first (rural homeowner with a tank), not trader-first. Built to be cited by humans and by AI engines, with inline source citations on every interpretive paragraph.

What this site is for

This site tracks the US residential propane price per gallon from the EIA Weekly Heating Oil and Propane Survey: weekly through the heating season, and monthly off-season on the months EIA actually publishes one (see refresh schedule). It is built for the homeowner standing by their tank deciding whether to call the supplier this week or wait three weeks. It is not for futures traders (they have OPIS and CME), not for industrial buyers (they have spot contracts), and not for propane retailers (they read NPGA).

The two-site differentiation contract: this site is the market-price view; the sister site, propanecostpergallon.com, is the household-cost view. The two sites are halves of one decision tree.

Data sources

• EIA Weekly Heating Oil and Propane Survey, residential series (W_EPLLPA_PRS_NUS_DPG and per-state W_EPLLPA_PRS_S**_DPG)
• EIA Weekly Heating Oil and Propane Survey, wholesale/resale series (W_EPLLPA_PWR_NUS_DPG; EIA's own name for it is "U.S. Propane Wholesale/Resale Price"). This one is not a survey EIA runs. See what each price is
• EIA Mont Belvieu daily spot series (EER_EPLLPA_PF4_Y44MB_DPGD)
• FRED Mont Belvieu mirror (DPROPANEMBTX, alternative with API access)
• EIA Short-Term Energy Outlook (STEO, published monthly)
• EIA Winter Fuels Outlook (annual, October)
• EIA Weekly Petroleum Status Report (inventory levels)
• EIA Today in Energy (context articles, especially polar-vortex and supply disruption episodes)
• EIA State Energy Data System (annual propane price by state and by end-use sector; the only place EIA publishes a commercial propane price)
• NPGA and OPIS. NPGA is background on market structure only and no figure here comes from it. OPIS is different, and the distinction matters: OPIS sells a subscription we do not hold and we quote no OPIS product, but OPIS data does reach this site through EIA. EIA's methodology states that " Wholesale propane prices are provided to EIA directly from OPIS", and EIA then weights those terminal quotes into the free state, regional and US averages this site uses. So the weekly wholesale figure here is OPIS-collected and EIA-published, and we name it that way rather than calling it an EIA survey reading
• Maine Department of Energy Resources heating fuel prices (statewide plus five regions; surveyed weekly September through April and every other week May through August)
• NYSERDA average propane prices (statewide plus six regions; surveyed weekly September to March and twice a month April to August, read from the New York open-data series behind the dashboard)

What each price is, and who collects it

Three prices run through this site and they are three different measurements, not one price at three points of accuracy. Treating the middle one as "what your dealer paid" is the mistake worth avoiding, and this page is where the distinction is kept.

Two consequences follow from the middle row and both used to be stated wrongly here. First, the wholesale price is a rack quote taken free-on-board at a terminal with the buyer arranging their own transport, so the tanker-truck haul from that terminal into a local distributor's storage sits above it, not below it. Second, EIA does not survey it: the terminal quotes come from OPIS and EIA weights them into the published averages. The wholesale vs retail page splits the hub-to-homeowner gap on that basis.

Refresh schedule

EIA documents two collection cadences, not one. In the heating season, "During the heating season (from October through March), this survey collects prices every Monday for these fuels." Outside it, "During the non-heating season (from April through September), the monthly survey similarly collects prices for these fuels on the second Monday of the month for use during the subsequent heating season." Readings publish at about 1:00 p.m. Eastern on Wednesday: the Wednesday of the same week in the heating season, and the Wednesday of the week following the second Monday off-season.

That is the rule. The practice has drifted away from it, which is worth knowing if you are waiting on a number. EIA published all six off-season readings in 2024, two in 2025, and none in 2026, and its survey page now states that "Weekly heating oil and propane prices are only collected during the heating season, which extends from October through March." with residential and wholesale price data due to return in October 2026. This site therefore does not promise an off-season reading, and it does not claim EIA has a rule against publishing one.

While no residential reading is being published, the freshest signal on the site is the Mont Belvieu daily wholesale series, which EIA publishes year-round, plus two state energy office surveys described below.

The off-season state survey layer

With no off-season reading published, the national residential figure is frozen for half the year, so the site also carries two of the state energy office surveys that keep running through it: the Maine Department of Energy Resources and NYSERDA. Each publishes a statewide average plus a regional breakdown with its own survey date, and between April and October those readings are months more recent than anything in the EIA series.

They are separate surveys from EIA's, with their own methods and their own price definitions (Maine, for example, publishes a 30-day cash or credit price based on a minimum annual consumption of 900 gallons). The site never splices them into the EIA series, never averages them into a national figure, and always prints the agency name and the survey date beside the number. Where a page shows the gap between a state survey reading and that state's last EIA week, it says the two are different surveys and that the gap is a direction, not a measured seasonal move. These two are the state surveys the site tracks because both publish a dated figure a reader can check; Wisconsin's Public Service Commission also collects prices monthly from April to September, and most other participating states survey in the heating season only.

How the data is pulled

Every site build starts with a fetch step: scripts/fetch-eia-series.mjs calls the EIA v2 API (api.eia.gov) and pulls the US national residential weekly series, the per-state residential weekly series for each covered state, and the Mont Belvieu daily spot series (365 observations). The result is written to a single structured file, data/propane-series.json, with a version block recording the latest EIA week ending, the fetch date, and the season state. If EIA is unreachable at build time, the previous file is kept rather than guessing.

A second fetch step, scripts/fetch-state-surveys.mjs, reads the two state energy office surveys into data/state-surveys.json: New York from the open-data series behind the NYSERDA dashboard, Maine from the Department of Energy Resources price table. Each reading is rejected if it falls outside a plausible delivered-price band or if its survey date cannot be parsed, in which case the previously recorded reading is kept with its own date. A figure is never carried forward under a newer date.

Charts are rendered as static SVG from that JSON at build time, not client-side. This keeps pages fast, screenshot friendly, and crawlable for AI engines that prefer static content. The version block is rendered in the page footer as "Data: EIA week of [date] | Page built: [date]", and in the data version stamp below.

Data version stamp (current)

Forecast page exception

The /forecast/ page is updated manually within 48 hours of each new EIA STEO release. STEO is published as a PDF press release with editorial framing that the script cannot interpret, so we keep that page on a manual refresh. Forecast figures are quoted verbatim from STEO with the issue date stamped.

What we do not do

• We do not invent forecasts. STEO is the only forecast we quote.
• We do not invent prices. Every price here comes from EIA (the weekly survey, the Mont Belvieu daily series, the Short-Term Energy Outlook, or the State Energy Data System) or from a named state energy office, with a date. FRED appears only as a mirror of the EIA Mont Belvieu series.
• We do not price anything to a source you cannot open. Every figure here sits in a free EIA table or a free state energy office table, and we quote no subscription product of our own. Where a free EIA table is itself built from paid data we say so instead of letting "EIA" stand in for the whole chain: the weekly wholesale price is OPIS terminal quotes, provided to EIA and republished by EIA at no charge (EIA methodology, April 2024).
• We do not display ads.
• We do not publish "best supplier" rankings.

Affiliate disclosures

The site does not carry affiliate links or sponsored product placements. Every price comes from EIA or a named state energy office with a date, and no propane supplier, distributor, or trade association pays for placement or coverage here.

Author and editor

Edited by the Digital Signet portfolio team. Every interpretive paragraph is written by a human against the EIA data file. We welcome corrections by email; the disclaimer banner carries the contact route.

Revision history

• 2026-10-04.Every description of EIA's survey on this site rewritten against EIA's published methodology (April 2024) and its table definitions. New section setting out what each of the three prices measures and who collects it, including that the weekly wholesale figure is a terminal rack quote supplied to EIA by OPIS and republished free. The off-season collection rule is now quoted from EIA rather than paraphrased, and the record of which off-season readings EIA has actually published since 2024 is printed in full.
• 2026-06-24. Per-state coverage expanded to all 38 states EIA publishes weekly residential prices for, adding 24 new state pages (Alabama, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Kansas, Maryland, Missouri, Mississippi, Montana, North Dakota, Nebraska, New Hampshire, New Jersey, Oklahoma, Rhode Island, South Dakota, Tennessee, Utah, Virginia, Vermont). Each carries the same weekly EIA series and PADD context as the original pages.
• 2026-06-10. Pipeline description rewritten to match the live mechanism (EIA v2 API fetch at build time; the original HTML-scraping script was retired after EIA changed their page layout). Six state pages added (New York, Massachusetts, Indiana, Illinois, Minnesota, Maine), taking coverage to 14 of the 38 states EIA publishes weekly.
• 2026-04-29. Initial revision. Site launch with full 2025-2026 heating season data and eight state pages.

Related

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