Which official number to type in
Two public series are the ones news stories usually mean. AAA publishes a daily national average of credit-card prices at the pump on gasprices.aaa.com. The Energy Information Administration publishes a weekly retail gasoline price, usually on Monday, in its gasoline and diesel update. Diesel is a separate series. A headline about “gas” that cites diesel is a different product and a different driver.
Your station can sit well above or below the national average. State fuel tax, a long drive from a refinery, and the blend sold in summer all show up in the local price. Type the number on the sign, not the national average, if you want your own bill.
Why the national price moves
Crude oil is the largest piece of the retail price, so a move in oil shows up at the pump after a lag of days to a couple of weeks. Refinery outages, seasonal fuel blends, and fuel taxes are the other large pieces. A news story that names only one of those causes is incomplete. The useful article names the series, the date of the reading, and the dollar change from the week before.
Keep one page current
When the weekly price changes, update a single explainer with the new AAA or EIA reading and the date. A second article titled for that month competes with the first and stops earning visits when the month ends. The calculator on this page does not go stale, because the reader supplies the price.